Plus hum, would you deposit large money amounts in a small fintech company ? The advantage of giant banks is that you sort of trust their size will make them able to weather a crisis, if only because so many taxpayers are involved that the government has no choice but to help.

A fintech with 1M users screwing up loan rate timings being unable to finance savings accounts and facing a run, would not have much runway and the government would simply slowly try to make people get 50c on the dollar and tell them to go back to a big bank if they want better...