So your options are three people who have absolutely no chance of getting even a single electoral college vote, let alone a majority. Or in other words, to potentially feed the spoiler effect.

Being a single issue voter doesn't make sense at the best of times, but when it means you're voting for someone who has no chance of winning and potentially helping an even worse candidate get into office, it's even worse. If we had ranked-choice voting on a nationwide count, it wouldn't be as bad (and would be fine if after you'd voted for those candidates on the one issue you actually weighed in between the major candidates), but that's sadly not the world in which we live.

Go ahead and vote third party if you're in a state like Alabama where there's no chance of a difference regardless. But in a swing state, third party votes can and do add up to lives lost.