I have a family member who holds onto gold and silver currency because he believes the USD is going to collapse someday. I've raised the argument you made with him, and he admits that such currency won't be useful in the midst of the crisis. He believes it'll be useful in the rebuilding period afterwards, though. I guess time will tell.
That scenario could be made of very long stretch of times. Gold is a shelter value (or so was I told). Hard to use as a currency (you need to buy small parts that can be divided easily - coins or ingots) and hard to hide/protect.
Gold is completely valid form of preserving wealth. Massive USD devaluation results is skyrocketing prices of gold. Why people think this leads to a mad max world I don't know. If USD is worthless, it just means people will start using some other currency.
