The 2-party system is a meme, and "wasted vote" people are sheeple following it. It is a meme in that lots of people believe that the 2-party system is unbreakable (based solely on the results of many 2-party-rigged election cycles), and it is self-perpetuating because people are willing to ignorantly claim-- as fact-- that a vote for a 3rd party is a wasted vote.
Not only that, but participants in/members of the 2-party system have rigged elections such that it is rare for people to gain exposure to 3rd-party viewpoints, because exposure is tied directlly to national polls, which traditionally don't even include 3rd parties to begin with.
If you really want to look at what a wasted vote is, voting for a "loser" in your district is a "wasted vote" because of the electoral college. But who can know who will win or lose to begin with?
It is damaging to US politics to continue perpetuating this meme. Decide what your issues are, and vote for the candidate you truly believe in. We should all cross our fingers that a 3rd party candidate (I support Johnson) can participate in televised debates this year so that we can see some common-sense, intelligently presented issues and viewpoints outside the scope of a "soundbyte."
I not only reject the notion of voting for the lesser of two evils (which is what I suppose I would do if I believed a 3rd party vote were a waste), but I also think that it is a short-sighted and unintelligent approach to democracy in general. In the worst case scenario, your 3rd party vote will bolster a statistic that can demonstrate the growth of a general discontent with binary politics; and, possibly, increase support for whichever party you believe in.