Yes but in the real world gold and silver etc. are rare. So as a result they do in fact keep their value.
Once again, you're thinking in terms of the
modern economy. Precious metals are rare on a
global scale. If they're common on a local scale, they're still worth their value on the
global market. If you're limited to a local market, and can only buy what can be hauled in a wagon pulled by livestock, things become
very different.
I doubt what you say about areas with a lot of gold suffering economic collapse is true. Why would being unable to buy stuff fast enough cause economic collapse? Just buy stuff as you need it, see the thing is areas rich in natural resources tend to do better than other places. Not fail epically because of too much wealth. What are these instances in history anyway? I have studied economics and history and I have never heard anything like that.
History + economics != historical economics. Look up what the Spanish economy was like during the 16th and 17th centuries. That would be the easiest, most well known, and most recent.
Yet again, you're thinking
modern economics. In the modern economy, a country can produce zero food and import all they need, as long as they export enough to not go too deep into debt. Freight ships and aircraft can easily transport enough food and goods to keep an entire comfortable.
But in an economy with horse-drawn wagons and sail-powered ships, the mass transit of goods is far harder, and all the money in the world won't "create" food or goods out of thin air. Industries must be built up first, and that requires time. Bandits and highwaymen aren't going to be stupid, and they're going to be attacking every caravan that leaves the hyperinflated country.
Without freighters and cargo planes, only a very small percentage of a country's daily needs can be imported at rock bottom prices. Thus the vast majority of goods must be farmed, crafted, and built locally. And
that means paying enormous amounts, because the currency is hyperinflated. Once again, this is
not a modern economy, you cannot merely go on the New York gold market, find a buyer in China, have him wire the money to your Swiss bank account, and ship the gold there by plane. In a pre-modern economy, gold value is based
partly on global rarity (what foreign traders who arrive once a year will give you for it), and
mostly on local rarity (what the trader across the street who's there every day will give you for it).
If total gold in the world suddenly doubled tomorrow, the value of gold on the
modern, global market would be half. Likewise, if a single country in a pre-modern economy suddenly finds itself with twice as much gold, the value of gold
in that country will be half, while it will still trade at full value with other countries. But you cannot import an entire country worth of food on horseback, not even if you
could fit an elephant cage on there.
So anyway, with too much gold and a hyperinflated currency, all locally produced goods cost more. Meanwhile, gold is slowly trickling out of the economy due to theft and trade. Do you think traders are going to go "oh, okay, the gold in the country was reduced by 5% over the last year, so we will reduce our prices by 5%."? No! They're going to stick with their hyperinflated prices, because they want money, and most people will have no clue how soon their total amount of gold will be back to normal due to buying imports.
So prices stay high, while the currency slowly deflates back to its former value due to trade. Bread continues to cost $100, even when the USD again trades at 60p. Once again, economic collapse. It's inevitable, without a carefully controlled economy, or global trade on a
massive scale. Neither of which were present in pre-modern economies.