Gamblers are telling stories about how they got banned because they are winning too much, I will like to tell you not to believe everything people tell you, these stories typically have another side of the story, there is a high probability that these gamblers have broken some rules along the way.
For reputable casinos, banning players that have won a lot of money legally is bad for their business, the casinos knows that the word of the mouth spreads faster than anything, so I believe that a reputable casino do their strong research before they use their ban hammer.
Before you take sides with gamblers claiming they get banned for winning too much, remember that casinos are good at monitoring and preventing fraudulent behaviors, you break some rules you are out, and no cheater want to admit that they cheat.
The gambler will know they loss huge money after the big money loss by the continuous game,till that he won’t do the releasing of the loss in the game.If the gambler who win and say his account get ban,ask him the gambling site name.You personally check that gambling site is real or fake.If the gambling site was good,two possibility of happening in your friends words.First he may do the lie to you,because you may ask loan for the benefit of yourself from the money he earned by their hard work.Second one is he get banned because of the wrong action against the site rules.