I get that kind of reaction a lot.
My brother is the gullible type. Tried to talk him out of a time share ski cabin. No luck.
When he eventually gave up on it and tried to sell it, he was crying that nobody told him all the pitfalls. Like you, I didn’t see any point in saying I told you so.
I think I understand how you feel. I have a few friends who make stupid financial decisions and it is hard for me to watch. Honestly I probably wouldn’t care if they would just shut up about it though. These people who feel like Arbonne (similar to Mary Kay) is a great way to make money and that playing the lottery will fund their retirement are the same ones who cry and bitch every month that they don’t have enough to cover the bills, they don’t know how anyone else manages to make money, they don’t know why they never have enough, etc. They will not put money into a 401k because they simply couldn’t afford to have that money taken from their checks but they can afford to scrape together $1000 for a pyramid scheme and then sob and moan when it didn’t work out. If they would have taken that same money and taken my advice to set up an ING account they could have earned 4.5% interest on it and actually made something from it rather than piss it all away. It isn’t wanting admiration or thanks for being a know it all, it is wanting someone to say, “You know, I think you are wrong about that, but thanks for trying to help” and then when it all goes haywire and they have nothing left not complaining about it because they were warned.
**According to Pliny
pbbth
Quiddity Glomfuster
AskNott **
thanks, at least now I know that I’m not alone 
You might also find it helpful to keep in mind that there are vast, manipulative marketing efforts trying to influence/brainwash people to get involved with MLMs and to gamble. Businesses are dead serious about this, because there is a lot of money to be made. They have put a lot of money and effort into how to influence people to spend money on these things, so you are up against something large, almost like alcoholism and drug addiction. You’ve probably noticed that telling someone who is addicted to something “You know, that’s bad for you. You should stop.” is totally pointless. Your best option may be to teach by example, by not getting caught up in those things yourself.
Again, I’m going to paraphrase from Dale Carnegie. Should you expect gratitude? Don’t be silly! (It gets a little religious, here.) When Jesus healed the group of lepers, how many thanked Him? I have to admit, I don’t remember if it’s one or zero. So, if a major dude like Jesus couldn’t get any props for curing leprosy, why should little you expect any better? It ain’t gonna happen. Sad? Yes. Accept it.