# Do casinos ever ban sports bettors who win too much? **URL:** \ **Category:** Factual Questions\ **Created:** [May 28, 2023, 6:10pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706 "2023-05-28T18:10:17Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![FlikTheBlue](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fliktheblue/32/10972_2.png) [@FlikTheBlue](https://boards.straightdope.com/u/FlikTheBlue)\ **Post date:** [May 28, 2023, 6:10pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/1 "2023-05-28T18:10:17Z")
A companion to the blackjack thread. Let’s say someone is really good at finding lines that are off, and over time they win consistently. Would a sports book ban such a person from betting? Would it make a difference if the gambler made it obvious, by only betting on a lower level division / league in an obscure sport, or only on a specific team under a particular set of circumstances? ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [May 28, 2023, 6:14pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/2 "2023-05-28T18:14:12Z")
Why? Sports books don’t have their own money on the line - it’s all parimutuel. The house gets its cut whether the guy wins or not. The only losers are the people who bet the other side to cover. ---
**Author:** ![Cugel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cugel/32/1199_2.png) [@Cugel](https://boards.straightdope.com/u/Cugel)\ **Post date:** [May 29, 2023, 12:46am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/3 "2023-05-29T00:46:45Z")
Popular opinion is that this happens in Australia, not 100% sure if it’s actually a thing > **[The little-known strategy to stop punters winning too much](https://www.abc.net.au/news/2019-01-20/gambling-how-bookmakers-stop-winning-betters/10708394)** > > You might be surprised to know that while most betting agencies are happy to keep the money rolling in from losing gamblers, start winning too often and it's a whole different story. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [May 29, 2023, 1:07am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/4 "2023-05-29T01:07:35Z")
> [@silenus](#): > > Why? Sports books don’t have their own money on the line - it’s all parimutuel. The house gets its cut whether the guy wins or not. The only losers are the people who bet the other side to cover. [That’s not true](https://www.forbes.com/betting/nfl/las-vegas-super-bowl/), tho the vast majority of the time they do win, and win big, while the public if they do collectively end up in the green will typically only do it by relatively slim margins. The example I recall was Super Bowl 13 between the Cowboys and Steelers. The most common line was Pittsburgh -4, and the Steelers won by 4. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [May 29, 2023, 1:33am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/5 "2023-05-29T01:33:18Z")
Typically, sports books will adjust their lines to balance the action between teams. If they get a perfect balance, they get the vig with no risk. This is preferred. There are times when they can’t or won’t balance the lines. One is the rare occassion they think the public is wrong so they’ll essentially gamble their own money the other way. The other is if changing the line opens them up to a ‘middle’. For example, if both LA and New York fans bet their home teams more than they should, the lines in each city would have to diverge enough to keep the action balanced that other gamblers could simply bet both ways and guarantee a profit. So the bookies might have to suck it up and hope they don’t have to pay out too much. This is probably more likely to happen in big games like the Superbowl. As for barring big winners…The best sports bettors in the world are lucky to beat the vig by 5%, and that is with HUGE variance. It would be a chore to even spot them. But the bookies don’t care, because the good sports bettors just take money from the bad ones. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [May 29, 2023, 2:43am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/6 "2023-05-29T02:43:42Z")
This article is seven years old but notes that in online Fantasy Football gambling the vast majority of the winnings goes to a very few. Almost everyone loses money doing it. > The rival startups prospered in football’s offseason. Both companies raised huge new rounds of investment, bringing [DraftKings’s total haul to $426 million](https://archive.ph/o/139lD/www.bloomberg.com/news/articles/2015-07-27/draftkings-scores-300-million-in-funding-led-by-fox-sports) and [FanDuel’s to $363 million](https://archive.ph/o/139lD/www.bloomberg.com/news/articles/2015-07-14/fanduel-closes-275-million-financing-from-kkr-google-capital), and both are now valued at more than $1 billion. To get to the size their investors are expecting requires a continuous stream of new players lured by ever-increasing prize pools with the help of muscular advertising campaigns. These ads never spell out a simple truth about daily fantasy competitions: While any player might get lucky on the back of a handful of entries, over time nearly all of the prize money flows to a tiny elite equipped with elaborate statistical modeling and automated tools that can manage hundreds of entries at once and identify the weakest opponents. [https://www.bloomberg.com/news/articles/2015-09-10/you-aren-t-good-enough-to-win-money-playing-daily-fantasy-football?leadSource=uverify%20wall](https://www.bloomberg.com/news/articles/2015-09-10/you-aren-t-good-enough-to-win-money-playing-daily-fantasy-football?leadSource=uverify%20wall) ---
**Author:** ![Horatius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/horatius/32/3572_2.png) [@Horatius](https://boards.straightdope.com/u/Horatius)\ **Post date:** [May 29, 2023, 2:46am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/7 "2023-05-29T02:46:51Z")
As explained in [this mid-80s documentary](https://www.youtube.com/watch?v=04KKWEOwgnM). ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [May 29, 2023, 3:25am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/8 "2023-05-29T03:25:38Z")
Isn’t another issue that persistent winning could be an indication of match fixing, or “insider trading”? ---
**Author:** ![FlikTheBlue](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fliktheblue/32/10972_2.png) [@FlikTheBlue](https://boards.straightdope.com/u/FlikTheBlue)\ **Post date:** [May 29, 2023, 3:21pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/9 "2023-05-29T15:21:43Z")
It could be under the scenarios I’m imagining. Something like a bettor who bets only on minor league Mongolian basketball and only on one particular team, or some other obscure sport. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 29, 2023, 3:35pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/10 "2023-05-29T15:35:29Z")
Horse racing, typically, is purely paramutual. There will be some odds posted when you place your bet, but those odds will be continually updated as more people place bets, in such a way that the house will always be guaranteed their take. And it’s the odds at the moment that the action closes that will determine how much money you get from a winning bet, not the odds at the moment you placed your bet. Most sports betting doesn’t work that way: When you place your bet, you know exactly which outcomes will earn you exactly how much. The casino will try to make it as much like paramutual betting as possible, by setting the line or odds in such a way as to get balancing bets, but it’s possible, if a large enough number of players behave differently enough from how the casino expects, for the casino to lose money. It’s just really rare, because the casinos are really good at predicting how people will bet. > [@Princhester](#): > > Isn’t another issue that persistent winning could be an indication of match fixing, or “insider trading”? While that could certainly be true, would the casinos care about that, so long as they’re still making their profit? I mean, if you came right out and told them you were fixing the matches, I’m sure you’d get in trouble, but are they going to put much effort into investigating it? On the other hand, of course, the relevant government might be very interested in that, as might whomever you’re betting against, and likely the league organizing the events that you’re betting on. ---
**Author:** ![colinfred](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colinfred/32/21338_2.png) [@colinfred](https://boards.straightdope.com/u/colinfred)\ **Post date:** [May 29, 2023, 3:38pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/11 "2023-05-29T15:38:23Z")
> [@Chronos](#): > > Horse racing, typically, is purely paramutual. There will be some odds posted when you place your bet, but those odds will be continually updated as more people place bets, in such a way that the house will always be guaranteed their take. And it’s the odds at the moment that the action closes that will determine how much money you get from a winning bet, not the odds at the moment you placed your bet. This is completely incorrect for most horse racing bets. There are some specialist bets like “the tote” that do operate that way. 99% of placed bets though will be at a fixed price. Edit: Never mind, checked it, and in North America most bets are like that, weird. ---
**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\ **Post date:** [May 29, 2023, 3:38pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/12 "2023-05-29T15:38:28Z")
> [@Sam\_Stone](#): > > It would be a chore to even spot them. If they did, they’d be smart to use their information to place their own bets elsewhere rather than banning them. ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [May 29, 2023, 10:58pm UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/13 "2023-05-29T22:58:21Z")
> [@Cugel](#): > > Popular opinion is that this happens in Australia, not 100% sure if it’s actually a thing This is extremely common among corporate bookmakers in Australia but generally applies to punters that bet on racing rather than sports gamblers. Most of the sites that provide betting advice will have something like this: [How do I avoid getting banned by the bookies?](https://www.winningedgeinvestments.com/posts/how-do-i-avoid-getting-banned-by-the-bookies) Governments introduced minimum bet laws to stop bookmakers simply refusing bets from successful gamblers. ---
**Author:** ![Cugel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cugel/32/1199_2.png) [@Cugel](https://boards.straightdope.com/u/Cugel)\ **Post date:** [May 30, 2023, 12:51am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/14 "2023-05-30T00:51:38Z")
> [@colinfred](#): > > and in North America most bets are like that, weird. I learned that in another thread about gambling, had me dazed and confused as well. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 30, 2023, 1:54am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/15 "2023-05-30T01:54:47Z")
USAians are equally perplexed about how race booking is commonly done in the Commonwealth countries. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [May 30, 2023, 1:55am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/16 "2023-05-30T01:55:19Z")
> [@Chronos](#): > > While that could certainly be true, would the casinos care about that, so long as they’re still making their profit? Couple of reasons. Firstly at least in Australia gambling is under constant pressure - via government - from those who regard it as a social ill, and criminality is used as another reason why it should be shut down or subject to greater regulation. Secondly, if someone makes a success of cheating, the cheating will grow and then it will become public knowledge either through rumours or someone getting caught. That will put many potential average joe punters off because - if they don’t have the inside information - they will feel they are being fleeced. ---
**Author:** ![Spoons](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spoons/32/3141_2.png) [@Spoons](https://boards.straightdope.com/u/Spoons)\ **Post date:** [May 30, 2023, 2:00am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/17 "2023-05-30T02:00:08Z")
> [@LSLGuy](#): > > USAians are equally perplexed about how race booking is commonly done in the Commonwealth countries. Nitpick: Race booking using bookies is not done in Canada, a Commonwealth country. It’s all parimutuel (the tote), and the odds are expected to change. Heck, here in Canada, I can bet on American racing; and once, just for fun, I bet on Canadian racing from a race book in Las Vegas. But everywhere in North America, even in Las Vegas, horse racing is booked through the tote. ---
**Author:** ![Cugel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cugel/32/1199_2.png) [@Cugel](https://boards.straightdope.com/u/Cugel)\ **Post date:** [May 30, 2023, 7:40am UTC](https://boards.straightdope.com/t/do-casinos-ever-ban-sports-bettors-who-win-too-much/984706/18 "2023-05-30T07:40:32Z")
They’re a multiplier of your stake. That’s it.