If Schwab is paying 0.45% and putting the cash in the money market at 4.5% they're pocketing 4%. If their clients go buy the equivalent Schwab money market fund

If Schwab is paying 0.45% and putting the cash in the money market at 4.5% they're pocketing 4%. If their clients go buy the equivalent Schwab money market fund Schwab just gets a few basis points in management fees.