If you can establish self-sustaining societies on multiple planets you eliminate humanity's greatest threat - the fact that Earth is a single point of failure.
If you can establish self-sustaining societies on the bottom of the ocean, you can be resilient to almost all of humanities great threats. It's technology that could also be used elsewhere in the solar system once it works well, opens up much more space for human habitation, and is also a much easier problem to solve.
Compared to deep ocean, space is easy. The rocketry is tricky, but you don't need to build foot-thick steel walls and, if something goes wrong, you can go outside.
Unless you are talking about bottom as in 10 metres down. That won't protect you in case something goes seriously wrong.
Never really bought that argument. So Hypothetically even if earth did get hit by another dinosaur killer or worse, wouldn't it still be easier to live here than on mars? at least the temperatures would be survivable and there is air and water here, much more so than Mars
Saying that the thread is about SpaceX and Mars and all I can say is "GO SPACEX!"
I think the idea is that Mars is just a stepping stone, and soon we'll be setting out for Alpha Centauri, Procyon, Tau Ceti, Vulcan, Betazed, Tattooine, and so on.
Hell, Zuckerburg, Yuri Milner, and Steven Hawking are already planning it:
More like a stepping stone to Saturn's moons and the asteroids. Once we get used - and capable - of living without a planet, there is little reason to bother with deep gravity wells.
> wouldn't it still be easier to live here than on mars?
Maybe. What if it's an artificial plague? What if any other number of catastrophic events cause the collapse of the civilization here?
Having multiple settlements elsewhere is insurance.
And, while Mars is one interesting place, there are other rocks we could easily settle and mine for resources. I don't think Mars should be the first we tackle (I'd go for the Moon first) but I'm perfectly fine with humans spreading all over the solar system.
The current big threats to humanity are climate change and nuclear war. They are threats we create for ourselves, by relentlessly expanding the economy and inventions of new technologies. Ironically our solution to it is to further expand our technology and economy into other planets.