[AlexanderHowl]

Mining asteroids for metals is not going to improve the carrying capacity of the Earth (it does not to address deforestation, soil erosion, mass extinction, global climate change). It also does not do much to damage the carrying capacity of the asteroid belt.

For example, 8 Flora is the closest of the massive asteroids. At a mass of 8.47 quadrillion metric tons, it could supply human civilization with iron for a million years before it ran out of ore. As a byproduct of producing 2.5 billion metric tons of iron per year, it would also produce every other needed metal without difficulty (for example, it would produce around 4,000 metric tons of gold per year). And that is just one of dozens of similar asteroids in the Main Belt.