No one votes for a third party presidential candidate because they think they can win. The decision is made on the basis of principle. Either the third party voter believes in the worldview, values and/or character of the third party candidate, or, as is the case for myriad Americans this election cycle, the voter is opposed to the worldviews, values and/or characters of mainstream candidates.
I have heard countless people say they cannot support Donald Trump or Hillary Clinton on these grounds. Some of these people are going to vote third party, and some are not going to vote at all.
I wouldn’t say that either group is necessarily “wasting” their vote, because they are standing up for what they believe in, but I would say that they should carefully evaluate which of their principles they are prioritizing.
Anyone who has spoken to me at any point in the last year knows that I do not like Hillary Clinton, and I do not like Donald Trump. Both have worked hard to repeatedly remind the public of their inadequacies. It seems there is always something shady or corrupt going on in the Clinton World, and Trump has shown time and again that he is simply a horrible human being with little understanding of the position he is running for.
Their policy positions do not give me much reason to support them either. However, they are the only two people who have a realistic chance of becoming the next president.
Although I have strong ideological and ethical convictions that I use to guide my political decisions, my North Star is the overall welfare of the United States.
I would rather do what helps the country most than take a symbolic stand with no practical consequence. Either Trump or Clinton is going to be president. That is the fact of the matter, and I would rather support the lesser of the two evils between them than support a third party candidate who will only ever see the oval office if he/she gets a special, White House tour.
National security welfare and economic policy are not going to be affected by symbolic stands. They’re going to be affected by the decisions of whoever wins the White House, and I want a say in that.