Gambling isn't necessarily zero-sum in utility, which is what matters. There's entertainment value for example. It'd be like saying the foreign exchange market

Gambling isn't necessarily zero-sum in utility, which is what matters. There's entertainment value for example. It'd be like saying the foreign exchange market is zero sum, because one party loses HKD and another gains USD. This is obviously flawed because utility is being gained by both parties despite being zero sum in dollars.