There are multitude of reasons why a gambler may be banned in a casino. Whether it is because of suspicious activity or misconduct, the casino doesn't just ban or restrict a gambler for no valid reason.
I like the away you put it from your last statement. the casinos don't just ban a user without any reason, when we are gambling, we are to also pay attention to their ToS, because this will be what will determine the longevity of our stay together with them on the platform, I've seen a situation whereby some gamblers have attempted on cheating on the gambling platform by making several attempts, so those that disobey will definitely receives the consequences to their action as being banned.