Pass a law. Disaster insurance maxes out at 95% compensation. (Same for federal insurance of bank accounts.) Not enough of a worst-case cost to cause a run on

Pass a law. Disaster insurance maxes out at 95% compensation. (Same for federal insurance of bank accounts.) Not enough of a worst-case cost to cause a run on the banks (or a collapse in property prices), but enough to get people to start using the brains they were born with.