it's quite sustainable i'd bet. banks traditionally make money by lending most of its deposits to other people and earning interest on that lending. as long as

it's quite sustainable i'd bet. banks traditionally make money by lending most of its deposits to other people and earning interest on that lending. as long as the deposits are large enough, that interest should cover the fixed costs (employees, infrastructure) and the variable costs (paying out interest, referral bonuses) of providing the accounts. internet-only banks also lower their fixed costs by foregoing expensive retail square footage.