It sounds like we're hedging our bets not a moment too soon. The extinction even Musk alludes to is not just the natural expiry of the planet. The end of human civilization could come from a natural freak cause or just a series of bad judgements. Nuclear war or other conflicts making basic food/water inaccessible to most/all humans may just be the tipping point for our civilization's demise. Every other planet or location we can inhabit is another option for civilization to survive on.