Why spend money mining something that will eventually be worthless?
See Mansa Musa and what he did for the world's supply of gold.
You don't seem to grasp how much of these resources are out there, in just NEar Earth Orbits.
The Asteroid Belt is thousands of times more packed with resources.
We will be set for an indefinite period of time, virtually endless resources.
Asteroid mining - Wikipedia
In 1997 it was speculated that a relatively small metallic asteroid with a diameter of 1.6 km (1 mi) contains more than US$20 trillion worth of industrial and precious metals.
[11][63] A comparatively small
M-type asteroid with a mean diameter of 1 km (0.62 mi) could contain more than two billion metric tons of
iron–
nickel ore,
[64] or two to three times the world production of 2004.
[65] The asteroid
16 Psyche is believed to contain 1.7×1019 kg of nickel–iron, which could supply the world production requirement for several million years. A small portion of the extracted material would also be precious metals.
Not all mined materials from asteroids would be cost-effective, especially for the potential return of economic amounts of material to Earth. For potential return to Earth,
platinum is considered very rare in terrestrial geologic formations and therefore is potentially worth bringing some quantity for terrestrial use. Nickel, on the other hand, is quite abundant and being mined in many terrestrial locations, so the high cost of asteroid mining may not make it economically viable.
[66]
Although
Planetary Resources indicated in 2012 that the platinum from a 30-meter-long (98 ft) asteroid could be worth US$25–50 billion,
[67] an economist remarked any outside source of precious metals could lower prices sufficiently to possibly doom the venture by rapidly increasing the available supply of such metals.
[68]
There are over 1200 1km+ diameter asteroids in Near Earth Orbit alone.
Asteroid - Wikipedia
This (asteroid) belt is now estimated to contain between 1.1 and 1.9 million asteroids larger than 1 km (0.6 mi) in diameter,...
Although fewer Jupiter trojans have been discovered (As of 2010), it is thought that they are as numerous as the asteroids in the asteroid belt. Trojans have been found in the orbits of other planets, including
Venus,
Earth,
Mars,
Uranus, and
Neptune.
So that is somewhere between 3 to 4 MILLION asteroids 1km diameter or larger. About 7% of these, 21,000 to 28,000, are M types and are around $20 TRILLION in value.