I doubt it is more about the profit in gambling, some people I know just gamble to spend their spare time but other gamblers usually play to make money. It depends on the person's perspective but the same end is expected for both category people. My opinion is the rich gamblers are less than other types of gamblers.
Well I don't know how true this fact of yours is but I kinda feel rich people have their fair share of numbers when it comes to gambling and even gambling addiction but its just that their own case is different because they are already made and their addiction doesn't affect anyone but for the case of the poor gambler for every penny they lose its as if they going crazy because of the shortage of funds.