You DO have the right to bitch about things, whether you vote or not. You have a constitutionally protected freedom of speech and not voting does not expunge that right.
You are presuming, quite arrogantly as I see it, that someone who doesn't vote has found or can find a candidate they are willing to support. Many people who don't vote find themselves unwilling to support either of the two talking parrots they are given to choose between and conclude the whole exercise if fruitless.
If you live in a state with very close elections it might be worth your time to select the lesser of two evils, or even a good and honest candidate should you have one available somehow. But we have a winner take all system and there are many people in this country who are effectively disenfranchised because they live in gerrymandered districts or districts with a large bias toward one party. Telling those people that they have no right to voice their discontent about the state of their government precisely because they recognize their own powerlessness to change it is extremely disrespectful and ignorant.