I can't recommend enough this blog post by Jason Brennan. Brennan, who authored The Ethics of Voting, a truly illuminating book, deals here with the silliest argument people use to convince others to go the ballot box: if you don't vote, you have no right to complain.
The idea behind this often heard phrase is that you shouldn't complain about the political situation if "you didn't do something that could influence government in the way you want it to go", which apparently includes voting. But, Brennan argues, individual votes do not make any difference: "On the most optimistic assessment of the efficacy of individual votes, votes in, say, the US presidential election can have as high as a 1 in 10 million chance of breaking a tie, but only if you vote in a swing state and vote for one of the two major candidates".
Brennan sees the "if you don't vote, don't complain" rhetoric as a signal of the still widely held view that people actually have a duty to vote in elections.
Among the few, passionate preachers of the right to abstain from voting, people tend to think differently: that is, non voting signals an understanding of the substantial powerlessness of political process per se to change things for the better. The non voter is thus somebody endowed with a far more realistic view of politics, who calls himself out of it because he finds it either immoral or plainly useless. Of course, there are nuances of this view: you can find democratic elections just a façade covering up the reality of power inequalities between the political class and anybody else, you may be frustrated with pork and special interests, et cetera. I think this is an exaggeration as well. It could well be that non voters are by and large people disinterested in politics, who do not properly appreciate how vast an influence Washington or Rome can have on their lives. But if they do not deserve unqualified praise and glorification (well, does any social group deserve unqualified praise?), they certainly do not deserve to be despised just because they do not vote.
Going to the ballot box is a choice: it is too bad so many democracy enthusiasts do not understand this rather simple point.