The point of exploiting ressources in space is not to bring them back to earth (to the ground, specifically), but to use them in space.
The ability to manufacture in space, when the price to orbit is about 3000 $/kg can be very lucrative.
Just refuelling in orbit for long-range missions, with the fuel coming from the moon (aluminium-oxygen for exemple) would be a game-changer, and the ressources to make it happen are not that out of reach.