The way I see it, the casino owner got the guy indebted to him and it's not like the debt is going to disappear anytime soon. It will continue to exist and weigh upon the gambler. If the gambler lives and works nearby he can be forced to pay up either in cash or in favors. He may be asked to work for free, or give up stuff that he owns, like a motorcycle or a car... The casino owner doesn't lose here, it's like he just got a slave for free.