If I was the manager of the casino, I will not fire my worker but I'll tell him privately not to yell gambler like that. It can be done politely and privately so it will have a better situation for the whole casino. About the gambler, it depends on the policy of the casino. As I have no idea about the policy of the casino for such case, I cant say anything how to deal with the gambler but I think banning the gambler from visiting the casino wont help him as he can move to other casino. We do not even know about the actual financial status of the gambler. Even if he keeps losing everyday but it does not mean that it is a problem for the gambler.