This all sounds interesting, but I don't really agree about the cost of mining bit. Yes, launch costs are high, but once you have all the stuff you need on-site on the Moon (or wherever, but obviously the Moon is cheaper than Mars or Venus), the only costs are getting workers to the Moon (and tired ones back home), and whatever it costs to send (hopefully refined) material back to Earth. Basically, it's a one-time cost to get the infrastructure up there. If you're doing enough mining up there (between the Moon, and maybe capturing asteroids and then refining them on the Moon, or in orbital or Lagrangian stations), then it would be profitable, of course assuming there's enough valuable ore there to begin with.
So it really comes down to a question of: what's the total cost of establishing all that infrastructure up there, plus the ongoing cost of actually operating up there, compared to how much you'll be able to sell the material for down here (taking into account time value of money of course)? With the huge up-front costs, it probably doesn't seem like it'd be worth it, but there's a lot of material up there between the Moon and the asteroids, and over a long enough time span it might make sense. Throw in space tourism (who wouldn't want to spend a week on the Moon?) and that should sweeten things. On top of that, launch costs are coming down thanks to the efforts of SpaceX and others. Ongoing costs can be minimized with heavy usage of either automated robotic systems, or with remote-control (or a combination of the two): with the Moon only a few light-seconds away, two-way radio control isn't such a problem as it would be for Venus or Mars. The fewer humans you need to regularly cycle there, the less things will cost to operate.
Now obviously, if the break-even time is 4 centuries, then you're not going to get many investors for that. But what if it's less, maybe only 30 or 50 years? It does seem like several billionaires are very interested in asteroid mining, among other space ventures. All it took for Columbus (today's namesake, even if he was a murderous bastard) to help start colonization of the Americas was an investment by the Spanish crown. What if some silicon valley billionaires pump a bunch of money into this, not really caring if they see a return on their investment in their lifetimes? (Plus, these same billionaires are also pumping money into longevity research, so if that works out and they live to 250, they might very well see a return.)