So you're saying that in an end of the world scenario where no monetary instrument has value at all and the skies are covered in radioactive clouds and you're leaving all your belongings and vehicles behind at your house that it's inconvenient to carry a million dollars worth of physical metals in your pocket while attempting to run away from the hypersonic nuclear missiles?  Okay. 

Stuff like this only applies to people who are dumb enough to live somewhere like Chicago or NYC during economic implosion or war in the first place.  Anyone living in a lower density area is already at the place everyone else will be trying to flee to.  And you seem to conveniently overlook the fact that in any scenario of mass emergency and migration, the economic system and infrastructure will have imploded, and the only types of things that have any hope of being monetarily useful are barter and physical metals anyway.