The only way that "mining" space resources possibly makes sense is if you're using those resources *in* space, to avoid launch costs. And the only vaguely plausible project anyone's proposed that would make massive use of resources in space is solar power satellites to supply power *to* Earth. SPS was a not completely ludicrous, but extreme long-shot approach to "energy independence" during the 1970s and 1980s, but senseless now that ground-based solar and wind + storage have flat-out won the argument about the future of energy sources.

All this stuff about "robotics" and "processing" in space has the slight problem of space lacking everything industrial projects on Earth assume, like water, air, cooling, and the ability to, relatively cheaply, send some guy out with a honking large wrench to pound some sense into the hardware.

None of this is in any way new. People have been looking at the economics and engineering of "space industrialization" for over half a century, and you can find extreme optimist tales of how great it would be for just about as long (see T. A. Heppenheimer, for example, or the L-5 Society). Sure, if launch costs drop dramatically new markets will open up, but not on a level that would justify a $2T company valuation.

All that said, I would be happy to send Dilbert Stark to Mars. If he does not return.