I don't subscribe to the belief that third party votes are "owed" to anybody. I've voted for third party candidates in the past, hoping to send a message to candidates from the two parties, with almost no success.
For a while, I worked as a realtor, and we would talk about the value of direct mailer postcards. The critical point was that you were trying to send a message to the recipient in the time that it took them to see your postcard and walk it over to their recycling bin. That was your window, and if your message took longer than that to digest, it was wasted.
That's how I think of the message you send with a third party vote. The message lasts as long as it takes for the party to walk your votes over to their trashcan. Your candidate won't win. If the message is strong, like say for instance the margin of victory is smaller than the percent of third party votes, they might remember you in the next election. Maybe. But they are just as likely to write it off as a fluke or an outlier, because that's easier than introspection.
There are two viable parties. You can support one or the other, or neither. But there is a clear difference between the two, and while you might not like everything about one party, there's going to be one party that stands for everything you hate.
You can vote against the party you hate, but if you don't, you can't really complain when they win and do everything you hate. Voting for a third party does nothing at all.