You know what would align the incentives beautifully? A law that says that if someone gambles money they can't afford to lose then they are allowed to claw the money back.
The gambler can get their mortgage money back, automatically gets banned from casinos, and maybe the casino would try to prevent the situation from arising in the first place.
Sorry, it's too late to edit my other reply, but it occurs to me that we have some similar rules to what you proposed in finance. Robin Hood had to eat millions of dollars in losses because they overextended leverage to some people who lost it all, because they were worried (in addition to the inability to collect all that cash) that regulators would find out they had overextended margin to people they should not have.
That's an elegant idea, except that people who gamble money they cannot afford to lose usually cannot afford the legal process to claw the money back. Maybe they claw back an additional 50% that goes directly to the lawyer who helps them?
The gambler can get their mortgage money back, automatically gets banned from casinos, and maybe the casino would try to prevent the situation from arising in the first place.