In the film ‘Contact’ the character Palmer Joss says I couldn’t with good conscience vote for someone who believes the other 95% of us are deluding themselves
I don't think this quote pertains to the same thing as the rest of your post. When you vote for someone you are choosing someone to represent you; so it's not about whether disagreeing with everyone makes them right or wrong but whether that makes them a good choice for a representative of those people.