Many Gary Johnson supporters are behind him because they refuse to sacrifice their principles in order to vote for the other two candidates, with whom they agree less (and often absurdly claim are virtually the same anyway). This is a noble theory, but there's one major problem with it - reality.
There are only three realistic outlooks for Johnson in this election:
1. He gets fewer votes than he expects, Romney's margin is larger than expected, so his few votes don't matter, Romney wins.
2. He gets about the number of votes polls show he might, or a few more, denies Romney enough votes to win a crucial swing state or two, Obama wins.
3. He gets far more votes than anyone expected, even wins a state or two (NM, NV, CO?), denies both Obama and Romney enough electoral votes to win, under the Constitution the election goes to the House, Romney wins.
That's it. There is no path to an actual victory for Johnson himself. The best he can hope for is to make a stand on issues and change the discussion and terms of the debate, as Perot did in 1992. That hasn't happened yet, and we have less than 50 days to go. In any scenario, one of the other candidates will win, either despite or because of his presence on the ballot. Johnson's supporters, while by definition ideologically, not politically focused, should understand that the vote they cast for him does have an effect, though it may not be the one they want. Whether they see a difference between Obama and Romney, there is. And whether they think they aren't choosing between them, their vote very well may make the difference in what has been so far the closest election in modern history.
Choose wisely Johnson supporters, for whether you want to or not, you may be choosing between the "lesser of two evils" for us.
NOTE: I supported Johnson in the GOP primary, but once he dropped out to run as a Libertarian, he lost me.