I think this is a case of insurance coverage. The fact that there's some implicit coverage of excess amounts is not sustainable long-term. Just like we buy insurance in the unlikely event that our house is flooded or damaged by an earthquake, so too should companies with significant assets in banks purchase, on their own, insurance to cover the potential possible, but unlikely, situation of a bank bust causing them to lose most of their bank account funds. In this way the government can focus on insuring the general public, and those "too big to fail" can get private insurance to cover their own risks. This is just my opinion and a possibility. Certainly if governments want to come to the rescue or we have a "survival of the fittest" with the loudest, angriest parties getting their way, then we can run things that way as well.