Nature is really the ultimate capitalist. Survival of the fittest. No safety nets, no sympathy for the losers... they just go extinct.
Nature is about equilibrium and balance. I'm not touting some spiritual mumbo jumbo either. Their are many examples where the fittest consume unsustainably and destroy their own environment in a sort of ironic suicide.
The ones that survive are the ones that live in harmony with nature, not necessarily the fittest. This is why we see so many balanced ecosystems in nature; because these types of systems are the only ones that don't overload and die out.
It's likely that humanity would survive the kind of event that lead to the extinction of the dinosaurs.
We have underground facilities and stores of food/water that would permit the species to survive an event that lead to the sun being blocked out for 5 years or so.
Sometimes, that's the best for which we can hope.