I think the comments here have a lot of logical, well thought out ideas. The thing is, who cares whether they will ever be able to do it or what the implications would be if they succeeded? The fact that someone is seriously thinking about this type of thing is just awesome. Regardless of whether they succeed or fail, the most valuable output of this won't be the precious metals. It will be the technical innovations that would be created in order to attempt to achieve the goal.

It's sort of like how the value of going to the moon was not just the PR and historical significance, but all of the technical innovations like satellites that ultimately came from that effort.