This probably has been discussed before but is worth talking about again.
The estimated volume of all gold mined on earth would fit in an 80'x80'x80' cube. That's it. Or it would fill a regulation sized football field to 4 or 5 feet. Or 4 olympic sized swimming pools with a depth of about 6.5 feet (2 meters). And when you realize that about 1/2 of all gold is in non-investable form, such as jewelry, industrial uses and held by governments, well, the amount of gold that the public can take possession of is small.
There's not a lot of it in existence. And that's part of the appeal. Supply/demand. Certainly less than 1 troy ounce per person in the world.
I was chatting with a young neighbor not long ago. Very smart guy. He asked what volume of gold would represent $1 million US dollars. When I told him a bit bigger than a 4" cube he scoffed at me. But that's about right.
It's heavy, pretty, malleable, non-reactive, rare, and has been recognized as a store of value for many, many centuries. Now imagine if every mutual fund, bank, investor and more decided that they needed some of this precious yellow metal.
I don't know when this will happen. Or if it will happen in my lifetime. But at some point, as Jackie Gleason would say, it's going to the moon...