Commercial banks experience runs when they write illiquid loans that they can't sell at cost as fast as people cash out. If they never write loans or only write

Commercial banks experience runs when they write illiquid loans that they can't sell at cost as fast as people cash out. If they never write loans or only write completely liquid loans that never default they will never get run. Tether could park all their assets in short term government debt and they would never have a problem, but they want to get higher returns.