I know folks change political sides a lot just as they change religions or other worldviews. I, myself, used to be one of those Bible-nuts. Now, I'm super-Liberal. That said, I am baffled when the change is the other way around. What would possess a person to switch from a worldview based on open-mindedness, freedom, changing the corrupt status quo, fighting "The Man", human equality, etc. into a worldview based on stodgy, closed-minded selfishness, bigotry, repression, hate, etc.? It blows my mind.
I think folks who go from Liberal to insanely Far-Right were just in the counterculture out of youthful rebellion rather than anything meaningful. They were Flowerkids, Punkers, etc. just to be different or "annoy old people".