Similarly, if you live in Utah, which Romney is going to win by 25 or 30 points, and you honestly prefer Johnson, then of course, vote for Johnson. If he can garner 10 or 15 percent of the vote, he is set up to run successfully in the future.
This is REALITY in at least 40 of the 50 states.
I stipulate that you can argue your single vote MIGHT make a difference in a "battleground" state (though only if tens of thousands like you also switch--your single vote won't make a difference one way or the other). But that is not likely.