It's really not over simplified. Our currency has been vastly over inflated by massive printing. Added to that is tremendous deficit over spending, year after year by the government. All with nothing to back it up.
Proof of that has been the rise of the price of gold, along with other precious metals against the dollar. In my lifetime alone I can remember going to the bank, and trading in paper dollars for silver dollars. Every bank had drawers full of them.
Naturally this was when our currency was considered valuable against silver and gold. Paper and ink was cheap then, just as it is now.