Actually, it is not a problem for you to take big risks as long as everything you have calculated, or that means as long as you have agreed with yourself that if you lose you will be able to take responsibility for the decision gracefully, but the main problem is that some people always want to get a big win but they are not ready to lose, This is what triggers more problems and downturns where it triggers emotions and when emotions dominate then obviously their crazy decisions they take without any hesitation, which in the end makes them fall into the abyss and not infrequently also some gamblers who end up stressed because they can not withstand various pressures.
Another thing is that I think it is true that there are always some gamblers who come with only the intention and purpose of entertainment and from what I have seen usually the goal is owned by the rich, the reason I think it is less likely to produce when the person already has the right way to make money that makes them rich. This means that yes as you said above that there are some people who are just looking for thrills and not money in gambling, but we come back to the fact that indeed the majority of gamblers are those who are too much in hope of winning.
I support your second statement, wealthy people are the ones you take gambling as a form of entertainment cause they already have enough spare cash to gamble with but poor people are the ones who take gambling as a form of making a fortune well most of them have been very lucky to succeed through it but such luck doesn't happen always else alot of individuals would've been very rich through gambling.