Sure, this can be done by advisors that don't have a balance sheet behind them, but their credibility hinges on attracting players with the money and having a track record of successful structures. Putting up your own money usually helps in that respect; when you start doing this consistently enough, hey, presto, you become a "bank." In the long run, we're all dead. John Maynard Keynes
Putting up your own money usually helps in that respect;
Putting up your own money makes you an investor, alonsgside other investors, and not an intermediary.
That's fine.
It's when you start creating credit on the basis of your capital that the problem starts. "Any economic unit can emit money. The serious problem is to get it accepted" Hyman Minsky
The credit intermediation I see as unsustainable mathematically - and I am not commenting on any moral issues - is the Basel I/II style creation of interest-bearing credit.
I am talking about banking reinventing itself as service provision, and I do not see that as inconsistent with your description of your profession of banking. "Any economic unit can emit money. The serious problem is to get it accepted" Hyman Minsky