if the global economy crashed so hard that the dollar was suddenly worthless, gold and silver wouldnt be worth anything either
This is where everyone gets it wrong. This is an outright incorrect statement.
If they are going to be looking for food and other things above all else, what are they going to trade for it? Despite any global crashes there's always something that people fall back on for
intrinsic value. Its always been that way with gold and silver. It never loses value.
Heres some good videos on the subject
http://www.youtube.com/watch?v=DyV0OfU3-FU Its part of a series. Educate yourself, it can be good for you.