$230,000
Invested in developing several properties. 2 office condos, fourplex. The the crash came bank stopped lending building money and demanded payments. Projects were not completed so could not sell any of the units to pay the banks. The LLC went bankrupt.
I stuck my Hank Aaron baseball card into my pocket for a day and ruined it.
I co-signed loans for two “friends”, both of whom proceeded to cease making payments to the bank. The total amount was $33,000. This was 14 years ago. I had to re-finance my paid for house. I am just now seeing the end of this nightmare. Never again will I lend anyone so much as a quarter.
Got a loan to help my brother get out of credit card debt charging 30% interest. He stopped paying me back after 2 payments. With inflation it’s probably worth about $20k now.
Since I learned not to trust him again, however, it was a comparatively cheap lesson. My brother is a very good conman and other relatives had it much worse. My aunt and uncle lost a significant chunk of their retirement funds on one of his scam “businesses.”
Remember that it’s never wrong to sell at a profit.
My financial advisor presciently recommended selling off all my regional-bank stocks just as the first rumblings on the 2008 crisis were starting to appear, but I told him I didn’t want to take a big capital gains tax hit in a single year. That mistake probably cost me about $50,000.
More recently, I fell for a Craigslist scam, and that cost me about $1,500. That one wasn’t totally my fault, though – the young bank teller should have been known, and told me, what a “check clearing” doesn’t mean – but I really should have known better (I was in a hurry).
15 Years ago, I ummed and aah’d over the purchase of a loft-style apartment in the regenerating ‘Shoreditch’ area of east London. It was £250k for close to 2000 square feet. I decided the area was still too lacking in amenities.
Those apartments now go for well over £4million :smack::smack::smack:
When I was 22, I paid $700 for an old Fiat Spider to a friendly old couple. They said they didn’t have the title handy, but would send it along when they found it. Ebery time I called about it, they were still looking. Maybe six months later the car died on me and I left it parked on a residential street. It was impounded before I got back to it, and the city said it had been towed from impounded by the lienholder, who had to be notified. Yep, they’d filed the title months before but put themselves on it as lienholders supposedly because “I didn’t give them the money to file for a new title.” (They’d also hurried to get the car out of impound out of concern for me.") I never asked them to, of course, but that started a rigamarole where it became apparent I’d never get the car back without paying more than I’d paid for it originally.
Reminds me of a story my dad told me when he was in college (in the 1920’s) of a friend urging him to invest in a company that was growing, and he passed it up…so he never did get stock in 3M…
As for me, I’ve loaned about $5,000 to various people over the years that I never got back; but to be fair, I knew it was a poor risk from the start and had the money to give without seriously damaging my financial situation. Probably my costliest mistake was letting the merchant in Jerusalam in 2013 talk me into buying a short sword and dagger set for $5,000…still have no idea why I did something that stupid, I don’t collect items like that and I can’t believe that they would be worth that much anywhere else. Dumb.
That would be an education, not a mistake. And it will probably be more useful than any college degree you could get.
I lent $15,000 I can prove (and a lot more than that, but I can only find paperwork on that much) out of my home equity loan to my ex. Well, he wasn’t my ex at the time.
On a related note, I sold off my video game collection in the mid-90’s on the notion that adults don’t play video games and didn’t get into the hobby again until about 2010, missing the entire golden age of retro video game collecting, mid-90’s to mid-00’s.
Had I gotten absolutely desperate, I would have asked him. But while I had to radically downsize, I was never at the point of desperation. I’ll see where I am come retirement time. If I need some help then, he and I have discussed it and he’ll provide it if needed.
I’m a really tough independent old cuss, which is probably serving me well in this instance. 
I had 3 Wayne Gretzky rookie cards when I was kid. Left them behind (with the rest of my childhood things) in the attic of our apartment when I was 13. In my defense I was only 13 and moving into a bachelor apt. shared with my mom and only took what I could carry. When my dad moved out of that apartment he left everything in the attic behind. 30 years later I’m still pissed off about it.
I was working for a company who got acquired. About six months later, my manager quit suddenly. I met him for lunch a couple of weeks later. He told me, “If the company ever promises you anything, get it in writing.” I didn’t listen.
I also let my father talk me out of buying some stock with money I earned in high school. My father is a wonderful guy, but he is not a shrewd investor.
Regards,
Shodan
Co-signed a vehicle loan for my brother. Vehicle was repossessed.
I once paid $7.48 for a membership to a free message board, several years in a row.
Bought £1,000 of shares that then rose to about £30,000 in value. I had bought through a friend because he already had a brokerage account so I called him and asked him to sell my amount. He said he didn’t want to get pushed into the higher tax bracket (he didn’t understand the concept of marginal tax) and couldn’t find the share certificate.
I decided to be polite and not push the matter and hey they’d probably rise even higher. Then the dotcom bubble burst and they’re now worth 80p in total.
If I could go back in time to 2004 and tell us not to buy a house two months before the bubble popped… Bought for $560,000, gave it back to the bank after they wouldn’t negotiate with us after my husband was unemployed for over a year, and they sold it to someone else in 2009 for $220,000.
Actually, I take it back.
By far the costliest mistake I made was saying “OK” when my wife said she was thinking of quitting her city job. Not only did we lose that income, but also the cushy government health insurance. Probably cost over $300K, that “OK.”