I've always assumed you'd melt the gold down and create coins or other tradable sub-amounts of the gold that you could exchange for goods and services. If people are still peopling, they'll still want a currency to transact with; if the dollar has failed then gold has a historical precedent that would probably make it easier to convince people to trade with you using it as a medium of exchange. It always seems like it's more suited to be an emergency measure than a plan A to me.

As far as I know, the idea with holding gold in bank storage is, that if hyperinflation occurs, the currency becomes worthless and there will be economic upheaval, but it will not be the apocalypse. And then a new currency will be created and everybody who held physical assets instead of the old currency will be in a way better position.

If society collapsed, resources required to survive have primary value. Food, water, clothes.

But the idea of money will still exist. Precious and rare metals will be worth something in a barter economy.

If you think it would be difficult to defend, you know it would still have value.

The easiest way to defend it is to keep it secret.

This is the way the world worked for a long time. That's why the idea of a treasure map exists.