In the simplest terms:
America has too much consumption and borrowing and not enough production and savings. There's not much of an option for an alternative. The FED runs the financial system and we have an oligarchy form of government. There's no incentive or reward for saving money. It loses value the longer you have it.
And, we also have a currency that is backed (literally) by monetized debt. That is NOT a sound currency. What little stability it has comes mainly from the oil being traded in US Dollars FIRST.
More complicated background of the 2008 Crisis:
You don't eve have to read. Just listen