Why do we mine precious metals from the ground, and place them in a basement vault?

It takes a lot of work and infrastructure to process minerals from the Earth. Some can be mined from a hole in the ground (open pit) and some have to be mined via hard rock mining (tunnels in solid rock). And it’s not about the resources themselves, it’s who gets the money from having produced those resources.
FYI: Consider this: All of the gold ever mined would make a block 10’X10’X about 100’ If mankind needed it all at once, how long would it take to mine it? It isn’t immediately accessible.

@kritiper On BloomBerg business news channel they frequently have commercials for goldmines that they expect a 200 million once of gold to be mined in each of the properties all over the world, that they own.

Unless they are All lying, it sounds like more than the 10’X10’X about 100’ amount that you listed.

What I stated is true. Check it out for yourself.
Keep in mind that gold is over 19 times heavier than water, so it doesn’t take much to weigh a lot. A standard gold ingot weighs 78 lbs. (936 troy ounces.)

I just did a quick, back-of-the-envelope calculation.
200 million ounces would be a block 10 ft x 10 ft x 3.5 ft. Amazingly compact!

A bird in the hand is worth 2 in the bush.

Gold and silver is mined because it is profitable.

Precious metals are reburied into concrete caves with iron doors to keep it secure until decisions can be made as to what the hell to do with it.