People don't buy gold because they think society will collapse.
Well, maybe a few people do - but the sort of redneck survivalists that have a basement full of tinned goods and assault rifles tend not to be the sort of people who can make multibillion dollar gold investments.
Investors buy gold when they don't trust the fiat currency issuer. If you think the treasury will devalue the currency (e.g. quantitative easing) then you buy physical goods to hedge against inflation. Gold is used because it is highly liquid (compared to other physical goods like property, antiques, art, etc.).
And FRPGs teach us that if you want to get quick gold, you outsource your production to a sweatshop in the developing world.