Don’t loan what they can’t afford to repay. Easy. Not everyone was stupid enough to offer debt up to people’s eyeballs, and many weren’t “fortunate” enough to even try.
Stupid games cause stupid prizes, for everyone involved. Bankruptcy exists for a reason and it was foolish to ever allow any debt to bypass it. Humans always have and always will act in their immediate best interests with a hopeful view of the future, and the best way to accommodate normal behaviour is to balance discouraging it (by encouraging the specialists in debt to refuse bad debt by punishing them with unrepaid loans) and ensuring the people caught in the system can still be functional in society since that is better for them, society, and everyone except the idiots who loaned them money they were never paying back.