I'm looking into organizing something like this. But this is warband. I feel like people would rather be robbed by a crazy bandit than give their money and pay a fee.
We're not talking of investment, cause it takes one guy to lend 1k to, bro never comes back to repay it. It's hoarding for protection.
I've run 3 banks/mutual funds for groups across various scenarios (Stauzis in Pax1, Belsier in Darkmyre, the Red Hand in CRP7), so I'll give you some notes on my experience, and that might help you decide whether these things are ever worth organising:
- I think you're basically bang on the money about WarbandRP not being great for investment banking - people rarely ever need to take a loan (in good faith; I'm not counting people who take loans fully expecting to scam the bankers or to force their FLs to get them off the hook) to buy anything, and when they do the rate of return is rarely going to be worth it for you on a scenario which has a limited lifespan anyway. - Banks are useless if you're using them as safety deposit boxes - nobody in their right minds is paying a fee for someone else (much less a FACTION) to hold their money for them. Banks don't work like that for a reason; giving your money to an institution to hold requires trust (and incurs an opportunity cost, but let's not get into that), and that trust is compensated for with interest by the bank, not the reverse.
These two facts combined basically mean a bank/fund is highly unlikely to ever be seriously profitable on WarbandRP unless staff throw you a bone like the mint on DNRP3 (spoiler: I'm afraid we won't). HOWEVER, that doesn't mean there's no place at all for a bank/mutual fund. All three banks/funds I ran ended up being way more useful as vehicles to accelerate gear development for the group I was running rather than enterprises to turn a profit. I developed the Red Hand's mutual fund in CRP7 in order to solve a common puzzle in WarbandRP economics: how do you ensure that everyone in your group is at least fairly well-equipped when some players are more active or more "productive" than others? The solution is for the more active/productive players to effectively lend their surplus cash to their less active/productive colleagues. Sure, this can be done person-to-person (this is actually a real thing called P2P lending), but that requires a level of personal trust between players who might not even be online at the same hours most days. Instead, if it's handled centrally by the faction/organisation, you can easily put in place a system which lets richer group members "lend" their money to the group, and get rewarded for it by weekly interest paid into accounts. Result - the Red Hand centrally equipped a crew of 8 with T2 equipment within 30 days (cost of about 36k, compared with the company's official earnings of about 13k over that timeframe).
tl;dr you're extremely unlikely to make money off of a bank, and your idea of using it as a glorified security deposit box system is possibly even worse than using it as an investment vehicle. However, they're extremely useful for organising your faction's/group's finances and making sure everyone in the group gets a chance to share in the fruits of everyone's labours.