You are right, no casino will purposely sell off their customers information to scammers because the casinos are already making too much profit from their company and I don't think their is any amount of money that scammers will offer the casino that will make them sell their customers information. Although, in some situation, it could also be possible that the staffs of the casino could be greedy to the extent that they will steal customers information from the cosino and sell it to scammers just to make extra bucks.
Unless the casino is actually out there to last for a long time, like they are not seeing enough profit from the business, too much winning, which is already exhausting their reserve on their first time of starting such a thing, if they want to exist, they can warrant the sale of customer information.
Another occasion where the selling of customer information can be done in the casino is by one of the staff members having a side deal with scammers. Without the legal concept of the casino's own, they can pick out a few user details they consider valuable and sell them off in exchange for whatever price they are being offered.