What you're really doing by saying "My utility function might value my self-perception as a person who votes for X" is phrasing virtue ethics as utilitarianism. That's a move which confuses rather than clarifies. If you value your self-perception as a person who votes for X, you aren't a consequentialist; you believe in virtue ethics. Can you say it? Yes; you can in theory be a virtue utilitarian. But no real-life virtue ethicists are utilitarians. Hence, confusion.

First of all, humans are 99.99% similar to each other. So I think we reasonably can have arguments about values. It's possible to be mistaken about what their values are. And people can come to agree on different values after hearing arguments and thought experiments. That's what debates about morality and ethics are after all. I don't think there is a human being that actually values ticking a box that says "democrat", knowing that it will have no consequence whatsoever. I think there are many beliefs and feelings that lead people to vote. Like "if everyone like me did this, it would make a difference", or perhaps "it's a duty as a member of my tribe to do this", etc. Some people cast spoiled ballots for similar reasons. Though they aren't changing the election, they believe just the statistic matters. Like how voting for a third party shows that the third party has some support in the population, and encourages them to keep trying. But all these arguments for voting are about some tangible effect on the world. And they could empirically be shown incorrect. E.g. maybe no one does read those statistics, or you live in a heavily gerrymandered district. Now imagine you find someone that really believes their vote matters. And somehow you explained all this to them and came to agreement that it really doesn't. And then they went and voted anyway. You could reasonably ask if they are being irrational. If they haven't really updated their beliefs. If their stated reason for doing a thing is shown wrong, and they don't change their behavior. You could ask them why they voted, and I doubt they would say "because it gives me good feelies" or whatever. Because people never say they do things because of that. And so somewhere they must hold a belief that is false and inconsistent. If they did admit that, at least to themselves, then fine. They are at least consistent. But then I think, they would probably stop voting. When people honestly admit the only reason they do