Following up a previous post, I've had a few more thoughts about some of these ex-"libertarians." You've got your high profile Bill Mayer types, then there's the social justice warrior I encountered, and then there's the communist I was talking about before. Interesting how they're all leftists. Also interesting how there's precious little evidence to suggest they were ever actually libertarians.
I'm beginning to think that a lot of these people never were libertarians, in the classically liberal, anti-state, pro-capitalism sense. They were probably disgruntled* "moderates" (read: modern liberals) who latched onto "libertarianism" because it was principled in its opposition to the drug and Iraq wars. They never understood the whole idea of free markets and economic freedom (maybe they confused it with the leftist "freedom from want" definition), and when they found out what all that entailed, they split for pinker pastures.
I might argue the same thing of the claims of frequent Objectivist recidivism: the people who backed out, probably never understood what they were dealing with in the first place. If they had, they either wouldn't have picked it up in the first place, or would have stuck with it.
That's my amateur psychologist take, probably 70% wrong.
*I know I'm not the first to ask this, but what is it like to be "gruntled?" It doesn't exactly sound good.