The US has enjoyed incredible prosperity since World War 2 due in fact to its dollar acting as the world's reserve currency and the institution of the petrodollar. (all nations trade oil in US dollars). The US used to be the largest creditor nation and now it is by far the world's largest debtor nation. The US government has printed so much money that the dollar has lost 95% of its buying power in the last 100 years. I could write 100 pages of info on hundreds of variables related to the collapse of fiat currencies but who would to read that many pages?
If you want proof, just compare the prices of goods and services you buy today from the prices of those same items 10 years ago. Has your income kept up with this increasing cost of living? So the question becomes what does the average person do to protect yourself from a money crisis? A quick answer is you buy gold as a hedge against inflation or insurance against inefficient government monetary policies. Think about this for a moment. You buy insurance for everything else in life; auto, life, house, fire, and vacation insurance to name a few. Why not insure your retirement?