What sorts of services did you have in mind for your idealized bank? Is it just taking deposits and making loans? Maybe automated payments? Any corporate finance stuff?
Payments. Loans. Corporate Finance. Those all sound necessary, ya. I think the product plan and it's rollout is really the secret sauce - even in a world where execution is everything.
high interest rate 2-5%, security, no annoying lockouts for international purchases, dont have to talk to customer service, no limits on atm withdrawals or phone checking (with invisible security).
USD prime is currently 3.25% so the highest you could expect risk-free* is maybe 3%