There are way too many rules to check and if people gamble without checking a single one of them, they are going to break at least one of them unwillingly. Not because they want to break the rules, but because they did not know the rules. It is vitally important to check ToS before you gamble in any place. Then people come here and complain about how their money is "gone".
This is why I believe that we will keep on seeing a lot of people who will claim most legit websites are "scams" because they did not read the rules and they broke one of them and their money was confiscated because of it and they will call it a scam instead of realizing they broke the rules.
The most important thing before playing on a website is to check how legit they are. I always have the impression that if you don't have multiple accounts, don't place crazy bets, exploit bugs,... then you will get paid (i.e. huge sums) after verification if it is a legit site. There are some sites that will not pay out any winnings at all, but if you do some research you know which sites to avoid.