"For example, there are millions of asteroids of different sizes and composition flying throughout space. One category, known as S-type, is composed of iron, magnesium silicates and a variety of other metals, including cobalt and platinum. An average half-kilometer S-type asteroid is worth more than $20 trillion."
Well, it's not like you are just going to grab the whole thing and bring it back. But I agree, a new source of rare metals would change the pricing. But, platinum is an interesting metal -- engineers could do a lot fun things with it if it wasn't so expensive.
An 800m iron asteroid would make a rather nasty weapon.... (about 75000Mt, probably considerably more than all of the nuclear weapons that have ever existed).
Also: The Universe is awash in energy; it is young, and full of hydrogen, much of it pre-packaged into natural fusion reactors for us. Most of it is available only on not-Earth. If it were actually feasible to put things in space we could use more of it without the issues arising when we try to do it in our biosphere.
Space is dead. Anyone who gives a couple moment's serious thought will realize that there is really no such thing as environmentalism in space; at best, there are aesthetic concerns. (Many people are not willing to be even that thoughtful, but one can only try so hard.) Some of the things we do on Earth would be better done in space, where the byproducts hurt nobody.
Earth does not have enough of certain resources for a really green society, based on the fact that many green technologies require various rare earths. Getting more palladium or platinum from space will enable us to build more fuel cells and such things. For bonus points, combine with the above and refine in space.
The problem isn't that space is useless by any means. It's not even useless to "the poor". It's just that there is a bit of a gulf between where we are now (communications satellites) and where it becomes really useful, even putting aside the technological advances that will arise in response that will be useful even on Earth (a lot of environmental systems work and such).
There's also the not having all our eggs in one basket, which is getting increasingly important. I do fear in the race between anybody's brother being able to build a biological uberkiller and having humans in space the former will win by a decade or four.
http://www.googlelunarxprize.org/lunar/featured-article/spac...