You should go look up false dichotomy.
The reality is there are at least four candidates in the race, and one of them absolutely will win. By not picking someone, you're allowing everyone else to choose for you.
This is why you perceive there to only be two candidates... years of people not voting for the others has weakened the system so that only two matter. It's worsened things for everyone, when you could have been voting for Libertarians forever and there'd be better candidates and a lot fewer taxes and laws that piss you off.
RE: The "If you don't vote, you can't complain fallacy"