Platinum from Asteroids. Many sought it. Technology fell short. Here's the answer, just released (Advances In Space Research, Elsevier):
https://www.sciencedirect.com/science/article/abs/pii/S0273117725001553

$1,370,000,000 in Pt from Main Belt asteroids per each 12-month mission, now possible.

Three innovations make this possible:

1. Fe and Ni are boiled off M-class ore, leaving platinum group metals behind. The twist is that the crucibles point TOWARDS the asteroid. PGMs are held in by centrifugal force because the crucibles (and heaters) travel around the ore body on twin maglev rails held aloft by a series of struts which are held down by a circumferential cable. This has a bonus advantage of capturing all that Fe-Ni and a double-bonus of coating the exterior of the asteroid in high-quality steel.
2. Fast Nuclear Thermal Rockets are fueled by uranium created ON THE MOON. This is an ULTRA-SAFE solution to the NTR problem (launching radioactive material through our shared biosphere). We transmute lunar thorium in situ to produce the highly-desirable fission fuel U-233. Travel from and to Low Lunar Orbit is possible in just 3 months.
3. A novel means of producing neutrons from NON-RADIOACTIVE deuterium using compact accelerators allows both Th transmutation and heating of kamacite ore from a metallic (M-class) asteroid.

The paper describes two competing architectures for billion-dollar payload returns of PGMs with a 1-year mission. One breaks even on the FIRST MISSION, while the other achieves superior long-term returns with $4.1B in profit from the first five missions.

Billionaires greedy for more FINALLY have a workable means by which to retrieve asteroidal platinum.

The rest of us benefit from cheaper fuel cells (and jewelry), plus ultra-fast transport capability throughout the solar system. Additional inventions (six patents and one patent-pending) open up the resources of outer space to the human economic sphere. Couple this with Space Solar Power (large photovoltaic powersats using low-density radio waves to deliver power to terrestrial receivers) from in situ materials and we can provide most of the energy and metals needed on Earth from space and stop gouging out pollution-generating mines down here.

But the biggest Wow factor in this whole approach is that we systematically hollow-out an asteroid while coating the exterior in a 2-meter thick layer of high-quality steel. Rotate that and we have a large-scale habitat with pseudo-gravity and the ability for large numbers of humans to live comfortably, and safely, off the Earth.

This cluster of innovations, centered on cost-effective platinum retrieval for high net worth individuals, could alter the entire trajectory of all humankind. Perhaps if we can follow this path, we will become a true space-faring species at the same time that we protect our precious homeworld from the tremendous burden we currently demand of Earth.

And, please don't forget, the platinum isn't just for the rich to get richer. With a lower-cost catalyst, fuel cells become affordable. We can finally achieve a Hydrogen Economy that runs our civilization using sunlight, water and air. This is sustainable, and available to all, for all time to come.