Yes. Banks give out loans. And they share a (tiny) part of their proceeds with their account holders! And the cost of this to the end-user is the risk that if

Yes. Banks give out loans. And they share a (tiny) part of their proceeds with their account holders! And the cost of this to the end-user is the risk that if everyone simultaneously tries to withdraw their money, the bank won't have it. That's happened once in U.S history. I think it's a safe enough bet.