Imagine you are the boss of a bank financed only by debt and next to no equity. Much of this debt serves as the money used by the public to pay their bills, while the bank’s assets are both illiquid and risky. This, you might assert, is a fairy story: nobody would lend to such a business. But suppose lenders were sure these debts were guaranteed by taxpayers. It would then become a money-making machine: all upside; no downside.