Abandoning the possibility of other options simply because you happen to be given one that seems to work for you is exactly what people do when they worship a god. Natural selection may have worked, and may continue to work, but that doesn't mean that it is the best option and that our environment hasn't changed too quickly for it to keep up.
Funny thing is, natural selection as an actual scientific theory applies to us no matter what we do, as it's simply a description of the process of some genes being replicated and some genes not. I guess you could completely curtail that, in theory, but it would take a hell of a lot of conscious effort to effectively make sure that every single member of a population breeds the same amount no matter what. In practice, it's impossible.
Also, our environment really hasn't been changing too quickly; I don't think so, at least. Right now we're probably a bit evolutionarily stagnant, because we're relatively comfortable. Of course, if we really manage to screw something up and cause some kind of awful near-instantaneous disaster, that would be bad, but especially for an organism as adaptable as humans are, I don't see us going extinct anytime soon.