The other point (which is really why I responded) is to note that space travel isn't just for humans. Robots, especially AI-driven robots, may be able to explore and exploit our solar system far better than bio humans ever could. It would make a nice division of responsibility: we get the Earth and her unique and valuable biosphere, they get the rest of the system and it's vast resources. I believe the relationship could be deeply symbiotic and fruitful for both cultures.