Thought about this, good idea, could start with a credit union or something.
the Banking licence is the key.
we need about 100M capital to look reasonable.
We can piggyback off existing banking infrastructure which is common for a credit union, and set out our constitution to be BTC friendly.
However, we have to consider the 3 hardest parts of the banking issues
[1] overhead costs
[2] compliance costs
[3] custody costs
This last one is quite expensive and hard to do. Custody of BTC if we go that path is not trivial. maybe we just openly DONT discriminate against BTC/Crypto source funds which means [1] and [2] are the issues.
how to fund it.
Banks rely on loan issuance and being a large enough loan issue to exist. with FRB, you can loan out about 10x, so 100M means we could execute about 1B worth of loans.
At 1~2% interest rate if that in repayments that's only $10 ~ $20 Million a year to keep the lights on, which is not really that much to manage everything.
If you went the exchange route, then yes you could collect the trading fees or better yet partner with say binance and take a cut, on the basis you are constitutionally crypto-friendly.
BTC custody is expensive though. Think through the safety, backups, the tech behind it to manage everything, plus make sure your own staff can't get hold of the private keys and run, this last point is very hard to do inmho.
I still see many people being puzzled by BTC, saying it's a bubble, that it's going to crash, etc...
Taking advantage of the huge price rise, I think some early believers should team and buy an existing bank. Not Barclays, nor JP Morgan of course, but there are small banks out there. Imagine a bank owned by bitcoiners, for bitcoiners. It would become an exchange, and it would be the best exchange in the world with the full ability to make Swift and SEPA transfers without the need to use the service of a third party.