The casino is an extremely rational savings model if you expected to constantly be robbed and want to convert small (and thus not worth robbing) income streams into occasionally large sums of money to be spent rapidly. I.e. say you are a north korean worker in China/Russia and you occasionally get small change to spend on cigarettes, you could gamble it every 'paycheck' and eventually buy a phone to escape with the winnings.

Filipinos have a more predictable low-loss version of this call Paluwagan.

It can also be a way to evade capital controls. You know you'll lose, but otoh you also know you'll probably not lose _everything_ and you buy in with RMB and cash out in HKD.