That said, I don't disagree that it matters, just not in quite the way you put it, that's a fantasy to me, a way to avoid the responsibility we actually do have, the responsiblity that is actually real. At the very least, mining asteroids beats scouring for ever more elusive resources on Earth. But humans living in hollowed asteroids isn't a solution to overpopulation and pollution. We can't build housing on Earth, but it's going to be so different once "we're in space". Yeah, right. Prove you can do it here or I don't believe it for a sec.
That said, I don't know _anyone_ who would advocate for colonizing Mars is a better solution that tweaking what we already have. It's a different solution addressing a different problem.
We should _absolutely_ be improving and addressing the problems that we have on Earth. I 100% agree with that. I don't see how that precludes us from _also_ starting the process of colonizing another planet.
It sounds like we agree at any rate.
Eventually, we should become a space-faring civilization if it is actually possible (big IF) there.
Not in our lifetimes, maybe. But if we colonize mars in the next 3 decades it seems likely that in 1,000 years human life on Mars could be largely self-sustaining.
When talking about creating planetary redundancy for human life 1,000 years is a small time-scale. We're guarding against 1/10,000,000 year kinds of extinction events on earth. It's unlikely that such an extinction event will happen on earth before a Mars colony could become reasonably self-sustaining.
That said, it's important that we do it _eventually_, because over 100,000,000 years the odds of that earth wide extinction event goes way up.