Did it ever occur to you that hundreds of whole new industries would be opening up at this time?

By definition, if you have the space transport technology to make asteroid mining cost effective, you can do LOTS of things in space to make money.

Frankly, I think the greatest uses for space-mined materials would be in space itself, particularly for less valuable ones like iron for steel. Building space colonies or solar power stations with the steel and other metals would be a very effective use (never have to enter or leave the bottom of a gravity well). It would also be easier than trying to figure out a way to drop bulk structural metals to Earth safely while still being cheaper than Earth-mined steel.

As long as the market is allowed to work, things will work out fine. At one time, aluminum was so hard to refine that it was considered a precious metal. Napoleon had aluminum tableware that was more prized than gold.

Then someone figured out how to make aluminum very cheaply. Can you look around and see what uses aluminum is being put to that maybe Napoleon wouldn't have predicted?