Because banks don't create their own currencies. The US dollar is backed the US. All banks are supervised and insured by that same government. If a bank takes

Because banks don't create their own currencies. The US dollar is backed the US. All banks are supervised and insured by that same government. If a bank takes on too much risk, a) there are people watching that, and b) the US can wind it up and pay everybody back. So a single bank failure causes approximately zero currency risk. As long as you stay under the FDIC limits, you'll get back every dollar you put in. Tether, on the other hand, is backed a bunch of shady characters who have been caught lying about what backs their currency. They claim it's 1:1 with US dollars, meaning that people buying Tether have no risk. But the more we learn about what they're doing, the clearer it is that it's not the case.