I agree with you.  It can't last forever.  They do have to keep interest rates low, to keep people borrowing money. Buying that new car, boat or house.  Which people stop doing, when the economy is bad.  Thus you reduce interest rates to encourage borrowing.  This is how the majority of currency is created and it is the interest from this "imaginary" money, that makes them rich.  If people don't borrow, they can't create more money out of thin air and charge interest on it. Which in turn means they can't pay their obligations and the whole system comes crashing down.