I don't really understand your point; the fact that preppers have gold and gold didn't help against zombies seems easily explainable by preppers not actually preparing for zombies, but instead far more realistic events including short term social unrest.
I don't see the value of gold if there is widespread chaos. Like a walking dead scenario, gold and diamonds are almost worthless. Guns, food, medical care is what's worth something in that chaotic environment. Of course we aren't defining the environment here.
1) it’s fun to TALK or THINK about some crazy synthetic situation like a walking dead scenario, but not many folks are really thinking about it literally.
2) it’s a lot less fun to talk or think (and may be dangerous to even try) about more realistic issues - like if you’re on the wrong side of the situation in Bosnia or Rawanda.
3) it’s the same kind of general process though, and some of the same tools can be useful to defend, escape, or repel.
And gold and diamonds got a LOT of people out of harms way that otherwise would be dead - at least from the 2 folks I knew that got out of Vietnam with their families when the south fell (and are probably alive today) only because they were able to bribe their way onto the boats using gold.