> As far as I can tell Brex literally just “lends” money to people that already have money. It hasn’t been clear to me that they’re even involved in any kind of actual issuance of debt in a meaningful sense at all.

It's exactly the same as Chase lending an individual Google engineer $5k for free for the month on his Visa card despite the engineer having $50k in his savings account already.

They make money on the interchange.