Precious metals are only worth something because other people want them. Because they think the metals are worth something because other people want the metals because they think they're worth something because... They're pretty, they're partly lasting and they're rare. Until they're not: aluminum used to be a valuable metal. Now I coat my armpits with it every morning, and half the metal objects I own are aluminum.
If you're expecting a big crash, you're better off purchasing items of utility or improving your land for raising food.