You might make arguments that when the world falls apart you’ll be glad you outsmarted us by buying gold or some other thing society decided has value. But if the world falls apart I wouldn’t bet on gold being the best thing to trade with. I’d rather have a stockpile of medicine, ammunition, livestock, and a seed bank. Those things are hard to store until you need them for an apocalypse. I can assure you that if you tried to give me gold for ammunition in this scenario you’d be leaving with gold.
You could also argue that gold/silver would and is a good currency abstraction and I’d agree with you. In the absurd scenario that the world falls apart I wouldn’t count on merchants coming around that actually want gold/silver. So many useful things become useless in an end of the world scenario that it’s not worth worrying about.