The financial system is debt based. So new currency, aka money, is created when banks give a loan.
With interest, the amount having to be paid back to the bank,
is greater than the original amount that was created.
This necessitates a new loan, otherwise there wouldn't be enough to cover the interest.
In this way, debt has to continue to expand. Otherwise it will collapse the present monetary system.
In Europe we had negative interest, set by the ECB. That is the opposite of growing money supply.
The law states that big institutions like pension funds have to invest in Government bonds. Which has destroyed those funds.
Japan is a great example.
Professor Richard A. Werner is probably the best expert on this issue.
Perhaps the documentary on Japans economy is a good place to start, if you wish to learn more?
Catherine Austin Fitts with
Solari Report, is probably the best source, in regard to the US economy.
Martin Armstrong of
Armstrong Economics is the best source, when it comes to the worldwide monetary system, with his Socrates computer.
As a side note. In the US you have fixed mortgage rates. Which creates issues like
pshufd explained.
It is different in europe, where mortages will have adjusted rates over time.