That was my point though - I don't personally believe that humanity is done for if we don't colonize other worlds - nature is a tenacious damsel, and we're at least half as tenacious as it, we'll find a way. I'm saying that it's the "public, noble reason" he put forwards. Deep down, I'm not certain his reason isn't "I'm going to Mars and that's that". Sure, his actions will benefit all of humanity - but his plan, first and foremost, is to either have himself or another person step on Mars just 'cause that's what he wants to do.

And that's the nifty thing about Earth - in theory, I'm pretty sure it's self-terraforming. From sunlight, thunder and elements, it created life. And then that life proceeded to survive 5 extinctions events. Humanity itself survived one - and without the tech we have today. There's only a few ways I know that could end that cycle of survival - and 90% of them is us, and we REALLY have to try (and life will be unbearable way before then - if humans have a certain driving force, it's absolutely comfort). As for Antartica looking like Eden - IIRC that's a stretch, as there's some places on Earth they use for simulating Mars - the only big disadvantage is that the atmosphere is thin and not breathable. Venus, on the other hand...

Anyway - sure, "why" isn't a bad question - I just find it tends to railroad thought threads. And I completely agree with the "Whoa" thing.