The political fanatic chooses his respective political party not out of any sincere desire for a better world, but because of his longing to be part of a team. It instils in him a false sense of identity, and he feels stronger knowing he is part of something bigger than himself, a wider community. To the political fanatic, politics is a game: my team vs. your team, democrat vs. republican, labor vs. conservative. "I'm with her". "Yes we can". Political fanatics are inherently anti-individualistic, because their entire sense of identity is molded by the ideas, opinions and preferences of the group, the collective.
Unfortunately logic, reason and critical thinking has little to no influence in the political fanatic's decision making, otherwise he would abandon his political activism altogether. But that would mean the death of his identity, his sense of belonging in the world, and the political fanatic would rather die than face up to that reality.
As for my own political affiliations, I don't have any. "I'm an anarchist, like any other sensible person".