How the founders of Brex built a billion-dollar business in less than 2 years

Or maybe do the dirty work of acquiring lots and lots of small companies and then sell them back to a bank in one package?

This is not meant to replace access to capital. It's meant to provide the same flexibility that a credit card gives to an employed individual. It allows small startups companies to simplify the way expenses are managed.

I have worked in a lot of startups where you will need to go and ask one of the founders to buy something that you need for work, because there's only one corporate debit card. My understanding is that Brex fixes this.

It definitely sounds like it's going to create bubbles. If companies help each other too much, then their success becomes increasingly artificial; all these companies become less efficient as a group and it's only a matter of time before companies outside of that cushy ecosystem catch up.

I think that eventually we'll get to a point when we collectively realize that the software development practices that we've adopted over the past decade are actually much less efficient than many other alternative approaches. For the past decade, the most efficient approaches and tools have been overlooked almost completely because they were developed outside of any VC ecosystems; so they didn't get any exposure or chance to prove themselves.

Selling to start-ups is a great way to build these products.

That has literally never happened before to my knowledge. See online payments with Paypal, robo-investing with Betterment, crypto-currency with Coinbase, etc.

The more likely scenario would be other startups rising up to compete with them, but it seems like these guys have a decent head start with 100 million funding and what looks like a compelling product judging from their traction.

They think they can, and they’ll try, and it’ll be a hot mess, and Brex will be fine.

There functionally is collateral. They monitor your bank account, you need min $50K in cash in it, and they only extend credit that's something like a quarter of your cash balance. It's a charge card, so you can't carry a balance.

It makes a lot of sense for cash-rich startups. The model doesn't work (in this form) for many small businesses.