Did you perchance vote for Gary Johnson for president? Then you wasted your vote on an unelectable candidate and helped Barack Obama's re-election.
The truth of a view does not depend on its popularity. But the political implementation of a view does depend on the electability of the candidate or candidates who represent it. If politics were merely theoretical, merely an exercise in determining how a well-ordered state should be structured, then implementation would not matter at all. But politics is practical, not theoretical: it aims at action that implements the view deemed best. Someone who votes for an unelectable candidate demonstrates by so doing that he does not understand the nature of politics.
Even if Johnson is electable in the sense of (i) satisfying the formal requirements for being president, and (ii) being worthy of the office, he is not electable in the specific sense here in play, namely, possessing a practical chance of winning.
When one votes for any unelectable candidate one merely squanders one's vote. If you are a libertarian, then your views are closer to those of Romney than to those of Obama. By voting for the unelectable Johnson, you help someone win whose views are diametrically opposed to your own instead of helping one whose views are partially consonant with your own. Now that is stupid, is it not? It shows a lack of practical sense.
If you won't vote for an candidate that does not perfectly represent your views, then either
A. you are a utopian who fails to understand that politics is about action, not theory, in the world as it is, as opposed to some merely imagined world; or
B. you falsely think there is no difference between the major party candidates.
The same reasoning applies to those who vote for Jill Stein. You are wasting your vote on an unelectable candidate. You are making a statement all right, but nobody cares and it won't matter. But I hope you lefties do vote for her: you will be helping Obama lose.