History - while America has always been governed primarily by two parties, that set of two has changed a couple of times.

Originally, it was the Whigs and the Democratic Republicans. In the mid-1800s, the Republicans were a new party, and Lincoln wound up being the first president from that party.

Interesting to note that the guy who freed the slaves was a Republican, while it was the Democrats who tried to maintain slavery. During the Civil Rights movement, the parties got confused about who their core constituencies were, leading to the major shift leading to the alignment we see today.

While I'm far from confident that it's happening, it's entirely possible that today's problems like ubiquitous surveillance, brutality of a militarized police force, etc., together make up enough of a sea change in public opinion that the Parties are again susceptible to getting lost. Witness flip-flop of many people in condemning GWB while failing to protest Obama's own similar actions, or vice-versa.

My comment above yours might answer that (a "wasted" vote isn't wasted if it causes change).

A few years ago I watched a TV program about Ralph Nader and it changed the way I voted.

Like most people, I had been voting for the least worst guy who I thought could win. I think that you probably do so as well. I probably did that for the first 20+ years. Now ask yourself: "How is that working out for me? Has it made a long term positive difference?"

The major parties really can't afford to cater to our interests, at least not in deed. We frankly can't pay them enough. Unless they are independently wealthy, they can't afford to run for another term if they don't satisfy the wishes of their donors [their true constituents]. Side with your voters against the guys funding your campaign(s) - no more money for you!

If you voted based on mathematics, you would see that you are mistakenly conflating your individual vote with the behavior of the general populace. For example, with the presidential vote, except in a couple small districts in swing states, your vote is completely irrelevant. Your single vote is both not enough to swing the state you are in, and even if it were, it's within the error margins for that state. If it ever got close enough to where one vote decides it (and it never has), it would be a court deciding the vote anyway.

So since your individual vote doesn't matter, you might as well vote your conscience and not pragmatically.