You can find FDIC insured bank accounts at 1.25% nowadays. There's also I-bonds at 1.9% inflation-linked, with a purchase limit of $10k/yr and a 1-year redempti

You can find FDIC insured bank accounts at 1.25% nowadays. There's also I-bonds at 1.9% inflation-linked, with a purchase limit of $10k/yr and a 1-year redemption lock-out. 3% is more accurate for the cost of margin loans or the opportunity cost of pre-paying a mortgage.