I just saw this as well. It effectively makes cash a L2 on BTC. The bank that FDIC insures $250,000 needs cash (liabilities far outweigh assets at every bank). River makes money on the arbitrage and likely the % of revenue they generate for Lead Bank. You benefit as a holder of both BTC and cash.

One problems is obviously trust of full reserve holdings of your BTC. But River has gone out if their way to show proof of reserve. You could always remove a given admit of BTC after you made a little.

Another problem is supply of Bitcoin eventually. ETFs bought 9x the new issuance for the month of OCT. This amount of interest in BTC isn’t sustainable for long unless the price of BTC in USD goes parabolic.