Disenfranchisement, as per most modes of radicality. I have observed as a near-universality among ancap types that they have identified at formative times of their lives as being "othered." They're not the in-crowd and they're not fundamentally of it. My suspicion is that they have a secret (or unsecret) opinion of themselves as misunderstood ubermenschen. (I recall that phase of my life, but then, I was fourteen.) With emotional and social development it became obvious to me, and to most recovering right-libertarian/ancap types I know of, that countless people helped me along the way because we decided, structurally and socially, that people should be helped. (We don't help everyone equally or sufficiently, and an expansion of it is decried by the you-got-mine, pulling-the-ladder-up-after-me types, but we try.)
I have made a pet interest of confronting the ancap types I occasionally run into--in tech, you sometimes stumble across enough of a True Believer to let their flag fly high--with questions of, what do you do when you're born into poverty? What is your recourse when you have nothing to sell? What do you do when somebody--but not the state, because the state doing it is Wrong, but Jim down the road with a real big gun and a couple muscley friends is just participating in economic activity--takes everything from you? The answers start evasively, but I've read as much von Mises and Rothbard as most of the vocal adherents and I can speak their language enough to fight on their own terms. Laughable handwaves of insurance companies and private security aside--and we called these "barons" in a prior age, but history and economics have already been laid aside to get into their weird twists of philosophy, so no it will not turn into feudalism, that's a silly notion--the answer is and will always be "and then you lose and you die". What chills me is that while most seem to have enough of an emotional intelligence to know that this argument doesn't win, I rarely hear even a shred of doubt when you finally get to that hard little core--because the idea of losing so totally as to be rendered economically incapable is not part of the equation. Other people lose, not them. This is also why there is so much overlap in this crowd of the worship of eat-your-dead meritocracy; that ancap nonsense devolves inevitably into feudalism is a feature, not a bug. Because they believe, as is their right, that they will be the knights, if not the barons and dukes and kings, of their new order.
I've run a few drafts of this post to leech out most of the pejorative nature I feel the ideas and the ideologues are due, and what remains should be taken more to be a mark of how truly alien (and I mean that in the sense of "inhuman") you have to get and how much reality you must pitch out the window at highway speeds to bend into a mode where the ancap arguments even make sense, let alone appeal. I am convinced that there is something rather fundamentally unwell about the whole thing. I have tried very hard to relate to it for years and my conclusion inevitably ends up being something around a predilection for cultish predations or never-outgrown teenage immaturity, and neither are satisfying but both fit the facts in evidence. I mean, I can have a discussion with a Communist. A Marxist and I are operating in a fundamentally relatable frame of reference. I don't agree with where they're going, but Marxists do not eject the entirety of human history to reach their conclusions--we can talk and actually agree what words mean. Every ancap I have ever met has washed their brains and adopted the weird sublanguage of the movement (Orwell was right...) and I can't do a thing with them except hope like hell they never stumble on a lever of power.