I don't know what a de-facto bank is. To me the term is associated solely with FDIC protection. Otherwise why would I give them my money in the first place? Their only purpose is to give me access to electronic transactions via a debit card, and if I can't trust that my money will remain in the debit card the whole system collapses. FDIC protection covers more than I need for access to liquid cash and I'd prefer to manually manage my long-term cash well outside of savings accounts.

(Note, i'm intentionally ignoring the many other services banks offer as they're all fed by willing deposits and are otherwise irrelevant to FDIC protections.)

Nonetheless, your description of the problem is apt and I largely agree.

And evolve just had a huge data breach triggering many business clients to leave.

One of the big use cases for me was/is the easy movement of money cross currency. Even something that should be easy like getting an IBAN as a US citizen is a pain/expensive without companies like Wise.

Savings accounts are a lucrative and relatively sticky offering. Many higher-rate savings accounts offer two (or more) tiers of interest, with higher rates applying to months where the customer does not withdraw or otherwise move money out of the account.[ß] The incentives mean that the customer is encouraged to deposit money INTO the savings account, but not take it out. If you don't have a full banking license, all that money is float - and you can invest it accordingly. Your net is the spread.

If you do have a full banking license, you can then use some of that sticky float for loans and earn a bigger spread. From what I have learned, small short-term business loans tend to be particularly lucrative, because the default rates can be impressively low. Big banks don't typically want to deal with those types of loans because the absolute ROI is simply lost in the noise and overall they do not move the needle enough to make a difference.

ß: you get access to better deals with less limitations if you have enough money to qualify for premier (or better) banking. The threshold is approximately the amount where the bank's wealth management unit becomes interested in you. I've told my bank that my absolute ceiling for any ongoing management fees is 25 bps and will manage my personal retirement funds accordingly. As a result they don't bother me, and I simply keep my fraction of investments at that bank in sufficiently low-cost instruments. I'm happy to pay my ongoing, sufficiently low management fees to them for this privilege.

Especially for savings. Using a fintech for day to day banking has its uses (I'm a customer of Revolut and N26) and they blow traditional banks out of the water in terms of features and usability (at one point my traditional bank was blocking "suspicious" card transactions from "abroad"... Ireland and Luxemburg, stuff like Amazon and Uber).

But savings are mostly fire and forget, unless you decide to play an active part which is not for everyone and most people shouldn't.