Completely agree on the point that putting hard constraints like living in space is a good driver for reusability and sustainability - tech that can be put in use on Earth later.
But let's look a little deeper why pollution is happening in the first place. Don't you think that people's greed and desires of having more and more things contributes to this at least a little? Overconsumption? Short-term profits? But what if we can fix _that_ at least a bit? Now that's a question I'm much more interested, since I believe it can have real effect and stop the runaway consumption culture.
Of course peoples greed contributes to this problem. Each and every one of us have some suspect ancestors in our gene pool. It's how evolution works, so saying "But we're greedy and we need to fix that first" seems silly to me - you're fighting millions of years of evolution. That doesn't mean that I want to see unfettered capitalism, but these problems won't go away by sitting around a camp fire and singing Kum Bye Ya My Lord.
Our consumer consumption culture won't change until it has to, whether that means folks going into space and living in an incredibly demanding environment or it becomes untenable on this planet. Wish it were different, but that's just how this stuff works.
There is money to be made in space (such as mining asteroids), but I don't think that's the biggest driver of going into space. If it was, you'd see much more emphasis placed on unmanned space travel. What we have instead is people motivated by exploration. When people first travelled to the North Pole, South Pole, top of Everest, etc... they didn't do so out of greed, I'd suggest they did it 'because it was there', for the challenge and wonder of experiencing somewhere new.
Colonies on Mars is kind of a grey area, only because Mars isn't the final destination, there's plenty more in this solar system/galaxy/universe to explore. There are some people who probably see it as just another place for humans to take over, but I'd suggest those aren't the pioneers, they tend to be the ones that come in later once the risks are reduced.
But let's look a little deeper why pollution is happening in the first place. Don't you think that people's greed and desires of having more and more things contributes to this at least a little? Overconsumption? Short-term profits? But what if we can fix _that_ at least a bit? Now that's a question I'm much more interested, since I believe it can have real effect and stop the runaway consumption culture.