“What’s the more wasted vote: endorsing a candidate who doesn’t win”
First, the vote is wasted not because a candidate didn’t win, but because when the vote was cast, you knew that the candidate can’t win (polls can be wrong, but not by that much); and because there _was_ a sill-undecided choice which you could have influenced, and you chose not to.
Second, a vote is not an “endorsement” of everything the candidate ever did, or of the candidate as a person. It is a judgement of the candidate’s relative fitness for the specific job, as compared to the specific other candidates. It is not a judgement about the candidate on any absolute scale. Saying that you prefer getting malaria to getting Ebola is not an “endorsement” of you getting Ebola.