> The whole idea of "third-party voting is a complete waste in the US" is incredibly dumb because a vote for someone who loses isn't a wasted vote.

Yes, but with a caveat, if you had a strong preference between the top two actually-likely-to-win candidates (assuming the third party wasn't competitive), it's at least not voting the most in your interests for the outcome. Which is why we really need approval voting, so we can actually vote for the candidates we like, rather than needing to "strategically" hold our noses.

But I agree with the rest of it, if none of the candidates represent you, the third-party vote at least allows you to send a signal of "I vote, but you need to make me want to vote for you, and this is what I want".