The central banks are currently controlling interests rates to levels that Govts can afford to pay on their ever increasing debts . This phenomenon only started in 87 before that the buyers set the rate by bidding for the bonds depending on the rate. The only way they can keep doing this is to issue more currency to buy it. The bond market is massive compared to the stock market and will eventually take back control and the rate will be set by the buyers of the debt. For example, would you buy a $1M 10 year US treasury for 0.25%. I wouldn't! And the CB's know this so they buy it so the market doesn't set the rate. It can't continue forever without creating massive inflation. So the currencies either become worthless through over issuance or the market sets the rate much, much higher. Either way it's bad.