I routinely see the meme that the opposition wins because their constituents are so stupid that they vote against their own self interest.
Well, there's nothing wrong with voting against your own self interest. Humans can be altruistic, and are capable of looking at a bigger picture, and these things can be at odds with self-interest. So voting against self-interest is by no means an inherently moronic thing to do.
Warren Buffet endorses higher taxes on the rich and an increased estate tax. Nobody takes him to task for campaigning against his own self-interest. In fact, most of us applaud his vision.
There may be some on the right who genuinely believe that saving the life of a fetus is a greater good than a more progressive tax code, or that other right-wing social issues are paramount to society. I think it's fine to argue against these things... but the argument that these people are voting against their own self interest is a poor one, IMO.