He can pull it off if he makes the first FDIC-insured crypto bank in the US, and do RFID phone payments. How this is useful is anyone's guess but he can integrate it with a Tesla taxi service and give people more upvotes if they spend more Musk Bucks. It wouldn't be a scam in such a case, just another low rent online-only bank competing with WePay and WU. There is probably a market for this especially if he gets big ticket names like the former President on board. There's enough idiots out there who can beilive FDIC-backed crypto is somehow better than FDIC-backed USDs.