Gold is rare everywhere; is there any evidence that there's a large amount of it floating around the asteroid belt?
There are individual asteroids out there with more platinum-group elements than has been extracted from the Earth in all of human history.
There is some evidence that most of the precious metal deposits on earth came from collisions with such asteroids.
I'd welcome the evidence about precious metals coming from collisions, that meshes with some of my understanding of the early solar system, but would be glad to know more.