Generally speaking, the lower the prime interest rate, the lower the returns on "safer" investments like certificates of deposit, sometimes below the rate of inflation. As a bank, why would you borrow from local depositors when you could borrow from the central banking system and pay less in interest?

People like my parents, who are both 65, could just park their money at a local bank and have an FDIC-insured savings instrument that roughly tracks inflation and helps invest in the local economy. They don't have to worry about cokeheads in lower Manhattan making bets that endanger their retirements like they have numerous times.

If they do that with lower interest rates, they're more likely to lose money instead of preserving it or slightly increasing it. Which, of course, gives the cokeheads more money to gamble with.