Think of it like this. You have a checking account and a savings account at a bank. You get nothing for an interest rate for the money in your checking account and the bank holds those funds. Your savings account however (if you would want one) gains interest revenue, as those funds are loaned out. In this example, the interest revenue gained on a savings account would be more than our current system offers (zero?) simply because banks need money to loan, and instead of getting money from the Fed at zero percent, they get it from customers' savings. Supply and demand of money. This increases the incentive of Americans to save money when interest rates are high, and makes businesses and investors less likely to borrow when interest rates are high.