And to add to your post, who would invest billions and billions...

And to add to your post, who would invest billions and billions of dollars to mine an asteroid to bring gold back to Earth when each ounce brought back increases the overall supply of available metal on Earth and thus reduces the value of that which you are mining.

Gold has myriad of uses, but for us, right now its primary use is as a monetary metal, to hedge failing fiat currencies. If we start bringing back a relatively unlimited supply, it is barely better than the fed. And as we all know increasing the money supply only devalues the currency and leads to inflation and lowered living standards over time.

By the time that we are advanced enough to spend the money and time and effort to be able to go out and mine an actual asteroid I would hope that we would have sorted a lot of our Earthly problems and that we wouldnt be going to try and increase our wealth, and instead would be going to obtain and use these rare metals to help advance society.