Many people are rushing into gambling when they hear about huge wins, they will think that it's a short cut to riches. They will use huge amounts to gamble and if they lose they'll begin to chase loses, in the end they'll become addicted. I believe that these are the category of gamblers that makes the casinos to be very rich because casinos only make profits from loses. People who gamble for fun and don't take it too seriously can not be addicted because they most likely gamble with amounts that they can afford to loose.
Perhaps every single partaker of gambling makes casino rich, no matter how small or big one gambles it increases the value of the gambling industry. Even without addicted gamblers the industry keeps increasing it's value because some who in their spare times gamble for fun the literally contribute to the wealth of the gambling industry, and here we aren't just talking about casinos profit, we are talking about the total industry however the large number of people in the world and how Gambling has been taking serious it's definitely going to amount to the billions OP is talking about in the industry.