Ross Perot carried 18.9% of the popular vote in 1992. He got 0 electoral votes. Gary Johnson managed to get 1% of the popular vote in 2012, and in 2016 he got 3.3% of the vote. Both times, he got 0 electoral votes. Jill Stein in 2016? 1% of the vote, 0 electoral votes.
President is not directly elected by popular vote (if it was, we’d have had Gore in 2000, and Clinton in 2016). They are elected by the Electoral College, whose electors are selected by rules of each state. Except for the states of Maine and Nebraska, electors are awarded to the popular vote winner for the state. So, a Libertarian or other 3rd Party cannot win the presidency if they cannot carry states (in Maine and Nebraska they could get an elector if they could manage to carry districts). Is this a bad thing? Is this a good thing? That’s a long discussion, but as of right now it is a thing, and one that cannot be ignored.
(Weird Note: 2016 was such a strange election, because of faithless electors – which had not happened since 1896 – Colin Powell got 3 electoral votes, and Bernie Sanders, John Kasich, Ron Paul, & Faith Spotted Eagle each got 1.)
Until a state elects a 3rd party governor, you are unlikely to see a 3rd party get electors in a presidential run.
If you want to break the hold of the two party system we have here in the US, then you need to focus on local and state elections, and convince your preferred 3rd party to do the same. I’d love to see more variety in our political parties, but this is simply not a game you can enter with a “top down” approach. You have to start at the bottom.
I bring this up because 2018 is a midterm election. There is no presidential race to drive up voting participation, so this would be the time to Get Out The Vote for those 3rd party candidates since the threshold for winning will be easier now than trying in 2020.
36 states will be electing a governor this year. Personally, I’m hoping for a lot of flipping Red to Blue, because I’m a dirty liberal, but I’d take flipping Red to Independent too.
Anyway, until 3rd parties start winning states, if you tell me you are going to vote for anyone other than the Republican or Democrat nominee in a presidential election, I will tell you you are “throwing away your vote”. By all means, you should vote, and you should vote for whoever you want, but in our existing system no one but the Republican and Democrat nominees are going to carry a state and get electors. You can vote for a 3rd party in protest, but it is a protest that those two parties will ignore, unless your 3rd party can prove it is worth paying attention to by winning state and local elections.