You don’t understand how FPTP works. It is designed to penalize people for voting for a third party (because it will always devolve to two parties. They may occasionally change, but it starts at the bottom, not at the oval office).

This “lesser of two evils” is a consequence of that. No one candidate is going to be best aligned with the majority of people. When there are two candidates, one will be more aligned than the other.

When a third candidate enters, they have to be closer to one of the two, and attracts voters that were more closely aligned with the primary party candidate.

So if you’ve got a close FPTP race, you could easily take a race that would otherwise be 51/49, make it 47/49/4, and even though the majority of people were more closely aligned with Candidate A, because some of them went for C, candidate B won instead.

Therefore, it’s foolish to abstain because you disagree with all candidates, because somebody is going to win no matter what. And it is foolish to vote for a third party, because they will not win, they will only detract from the closely aligned party, which in turn favors the less-aligned party.