"If you don't vote you lose your right to gripe."
Untrue, you have the right to gripe guaranteed by the Free Speech clause in the 1st Amendment to the US Constitution. Don't listen to the ranting of partisans otherwise.
Vote because you want to vote, not because you feel obligated to vote. Those who vote due to obligation are typically the folks who don't educate themselves and cast "straight-party" or incomplete ballots. I'd rather you not vote than mail it in.
You can still gripe.