If by virtue of greedy gamblers that abuse the bonuses system and a casino then decides to halt bonus offering to its customers that are due it. Such casino would only be making a bad business for themselves because it's going to drive customers away from the casino when they realise they are not getting bonuses anymore as it were even with how much they spend gambling.
Of course, a strict regulation can be helpful.
That is it. This bonuses from casinos is part of the fun gamblers enjoy in casino and when it is no longer coming, they would rather look for a casino where bonus is been giving to get more fun in gambling. Like I already said, it is the job of the casino to know how they can go about bonus for greedy gamblers not to take advantage of it because if bonus seize to come it gonna affect the casino, whereby some gamblers will go look somewhere else where they would get bonus from. Giving bonus to gamblers it part of the business of the casino which is very mandatory.