I think that if a person adheres to the rules of his religion, then he will not play gambling. The rest can gamble either for fun or for making money. Because it is very difficult to combine earnings and entertainment.
It totally depends on the religion and their belief. There are other ways to entertain ourselves if we are just treating gambling for fun but because there's money to risk it became exciting. In my view, money that earned from gambling is not different in other source to earn, its just that how you accumulate it is more on luck since you have no assurance if you'll going to grow your money or not.