It's my understanding that in the U.S. casinos reserve the right to ban anybody they want. I'm not even sure they need a legitimate reason to do so (anyone help on this one?). Casinos ban people if they think there is a hint of cheating--for example counting cards. The casino you went too might have thought that you employed some sort of 'cheating' system in order to win that much. I think the casinos look out for their bottom line: profit.

Ricky