Think the point of the website is implicit in the "Let's get to Mars" vision is that "Earth is an unsolvable mess and will be inevitably become uninhabitable". In other words we're failing to envision some kind of future for ourselves on Earth.

There's a great interview with Alan Moore (Watchmen, Walking Dead and much more) on YouTube that is highly underrated - https://www.youtube.com/watch?v=cBc71ROdGxU - the whole thing is great but at 4m32s he puts it beautifully...

"We tend to think, at this juncture of the 21st century, that there are only two possibilities regarding the future. One is the future will be exactly the same as today, only with smaller radios and smaller cars. So if the future is going to be the same as today, why bother preparing for it? The other alternative is there isn't a future. That is all ends in some kind of massive environmental collapse or a series of mushroom clouds. In which case why bother preparing for the future, if there isn't going to be one? Neither of these mindsets are actually doing anything to prepare us for the world in which we will almost certainly be living. Or which our descendants will almost certainly be living in. If you don't imagine a future, there's a fair chance you're not going to have one."

Elon's whole argument for Mars is based on the belief we don't have a future on Earth and that some kind of Dark Age is coming - https://www.theguardian.com/technology/2018/mar/11/elon-musk...

"If there’s a third world war we want to make sure there’s enough of a seed of human civilisation somewhere else to bring it back and shorten the length of the dark ages"

Personally think we should regard it with the same level skepticism we have for door-to-door salesmen. It's a great pitch to sell SpaceX...