Another answer: because regular banks are awful to deal with. They don't have nice APIs to just move money around. They apply velocity limits at surprising times. They can terminate your account suddenly for opaque reasons. They charge high regular fees and even higher "gotcha" fees if you make a mistake. They can take back money sent to you for up to 90 days, but often can't get back money you sent to crooks even if…
This 100%. I work at a fintech that's not a bank. Instead, we integrate with people who integrate with banks--we've basically got one middleman per continent (except a few). It's awful. Rather than having to figure out the regulatory details of each jurisdiction so that we can be compliant, we instead have to figure out the regulatory details of each jurisdiction so that we can trick whichever middleman into being co…
I talk to several Fintech startups a month complaining about this sort of thing. Forgive me if I can't quite gin up any sympathy. It's a business with centuries of baggage, massive inertia, vast resources, but what I typically hear is "I'm gonna Uber/Tesla/Bird this financial industry thing in 6/12/18/24 months, ignore the rules because 'disruption' and find someone else to push all the risk, compliance and governance issues off onto. I'm going to pretend it's not a cost of doing business and hope no one catches on before we find an exit and get rich". And now you're finding those 'others' aren't the suckers you wanted them to be, and that complying with regulations, especially across the world, actually costs money. Tons of it.
And most of all...real disruption is incredibly hard, no matter the SV mythmaking. The Fintechs that are going to be unicorns aren't complaining that the people they tried to outsource the hard parts of the business to aren't making all the hard problems magically disappear.