Quoted from Blake:
I have never looked into it but I will be! Probably depends on how familiar with it people are unless you can send direct to a routing number.
Thanks
Blake
You can't send direct to a routing number; rather, you send/receive to/from a verified venmo account, that MUST be linked to a bank account. Thusly, venmo is the in-between, and I'm imagining, makes money from people who don't immediately transfer their venmo balance to their bank account. (It takes 1 business day to transfer from your venmo account to your bank account for free (otherwise, its like a 3% fee to transfer instantly, hence my previous thought...)
I usually leave about $500 in my venmo account (even though transferring from your bank account to your venmo account is instant) just so I can snap up good deals when I see them in another hobby I'm into (where venmo is the preferred payment method). I'm guessing, aggregated over all the other venmo users who have money in their accounts, adds up to real interest money for them.