That our current methods are unsustainable? There are plenty of ideas for solutions.
That the current state of human cooperation is below the necessary threshold to achieve a self-sustaining society on Mars? Maybe, but I'm optimistic that we'll find the inspirational leaders that are required.
- Even if all of Musk's enterprises were aimed at colonizing Mars (like gp suggested), they can be quite useful here.
- Turning Mars into a self-sufficient habitat is both an absurdly long-term (and laudable) goal and no guarantee of survival. We have to worry about the problems of surviving on Earth today and, in the very long run, how to live in many other places.
(upvoted your comment, because I agree with it)
It seems to me that this really isn't the case. Our attempt to make a home here is causing a mass extinction, extremely fast change in atmospheric makeup (compared to historical models), depletion of fresh water reserves (in some areas anyways), increased frequency of bad weather, earthquakes, etc. Under a 'business as usual' model I have trouble seeing our current ecosystem supporting us for long (e.g. another 100 years).
In my opinion that's part of "knowing how" - knowing how to make something actually happen outside of theories. Hopefully we'll get there soon.