If A and B are both less preferable choices but are pretty much guaranteed to win and you vote for saint C who has no chance to win, what exactly did you accomplish other than satisfying your personal choice?
I vote for the person who represented my interests. Why would I choose someone who doesn't?
Because not enough people are voting like you to guarantee that your choice has a chance?
It would be different if most people were aware. The next best option is to go with the person you feel will do the least harm.
If that's the attitude you accept, it never changes, does it. Perot had a break through in 92. He didn't win, but he took almost 20% of the vote which hadn't happened in decades. If Gary Johnson was given the same media time that Trump and Hillary are and participated in the debates with them he could very well pull off the same thing, if not improve on what Perot did given how disliked the other two are.
Your logic sounds great but like I said before its not considering human nature. There are a lot of ifs but the most important if is if people change their mindsets. Its a well known fact that is probably the hardest thing for humans to do. The failure of those "other" candidates actually makes it harder for another one to get elected in the future. People want to "win" as you pointed out. To them thats more important than getting it right.
Let me ask you a question. If you knew your vote for another would result in someone you really didnt want to win being elected, say Hitler, would you still cast your vote for another?
I believe he likes the Moral High-Ground, made of sand.
"My vote didn't matter, maybe even made things worse, but I feel good about myself." That and a fiver will get you drink at Starbucks, but it won't help the country at all.
Here, if you don't vote for the lesser evil, the greater evil wins.