Except. Consider this — you live in France in, say, 2002. Your Socialist candidate has finished third in the first round of the voting — not far at all behind second place but definitely third — and in this system, like others, only the top 2 candidates prevail.
Do you support Chirac? He was perhaps to the right of Hillary after all. Or do you risk Le Pen becoming president?
That is the situation today. I agree with everything you say, except this. You are not “might as well vote Republican,” you are choosing to vote “Nationalist.” Trump is essentially the Know Nothing Party come back from the dead — or in modern terms — Fascist, Falangist, Golden Dawn.
You and I are not the first people on earth to face this choice. Just a generation ago Richard Nixon got a 6 year lease on the White House because the left stayed home. George W. Bush could contest Florida 16 years ago because of Ralph Nader’s vanity.
Elections do have consequences.