With other precious metals than silver and gold, their stories are very different.
Platinum was not discovered until 1557, and identified as such in 1741, while gold and silver are known to man since 4.000 BC. Obviously this metal has an anecdotal role in the pre-modern history.
We must add to this late discovery that resources were extremely limited until the discovery of the largest vein until then and since. South Africa would actually have over 90% of global platinum reserves; some estimates go as far as saying that there would be up to 95% of reserves. The country provides “only” 75% of global production; Russia supplies 13% of platinum and other producers that are too small to be worth mentioning.
Let’s put aside recycling, industrial equipments are often recycled but the raw material doesn’t go back to the market. There would be 66,000 tons of global reserves, and at the current rate of exploitation we will still have the next century. In view of this, it becomes dared to project that far into the future. Therefore, we aren’t going to take the risk.