A common talking point for who hate right-libertarians is the "libertarian to alt-right pipeline". Most libertarians of course deny such a thing exists, and understandably so because it's extremely insulting and it's not obvious what would cause such a pipeline. I denied its existence too until I was forced to admit my own mentor was an example. So, I want to explain to the best of my understanding why it happens in the hopes of convincing libertarians that it exists, giving them advice on how to prevent it, and convincing non-libertarians that it doesn't indicate any moral defect in libertarianism itself.
It all starts from having the wrong reasons for being a libertarian; hence why it seems exclusive to deontologist libertarians (or at least the really bad cases are), and particularly those who trot out argumentation ethics.
The first point of interest is that this justification for libertarianism locks them into an unreasonable belief that property rights are totally indefeasible. I have asked many an ancap whether it's okay to steal to survive, and from those that use argumentation ethics, the answer is invarably "no": they would be disgusted with any able bystander for refusing to help, but would not condone violating property rights for it. Because to admit that degree of need makes any difference at all would contradict argumentation ethics.
This is how they depart from conscience as a source of moral judgements. The next question, if they're so loyal to this NAP, is how they get to justifying obvious NAP violations like borders - psychologically how, that is. Well you see, deontological ethics are really psychologically brittle. Their judgements can swing wildly based on an insignificant difference or mental gymnastic. Especially when combined with a rejection of proportionality of force and after being completely detached from conscience as a source of judgements, all it takes is the existence of some act of aggression causally connected to immigration (the welfare state). It's false that the existence of a welfare state makes immigration aggressive, but all an ancap psychologically needs in order to do this is that it's somewhat complicated, so it's easy to use mental gymnastics to convince yourself that keeping immigrants out of a welfare state counts as a defensive use of force in some way, and once you do, that's all there is to it. Automatically no limit to what is justified to do to immigrants and no opportunity for the logical error to be caught by conscience because argumentation ethics users don't believe in conscience.
They can do this to themselves on other issues, like Nullus Maximus did when he advocated outlawing victimless acts (wearing masks) and using government funding to fight muh Antifa terrorists. Because of the complexity of interpreting it, the NAP is absurdly vulnerable to this kind of gymnastic. Before long, you can be a "libertarian" "anarchist" who supports a fascist police state in the hopes of it crushing your non-state enemies.
While this explains how the NAP can be twisted to endorse the opposite of what it's supposed to, that doesn't fully explain why the alt-right pipeline happens. After all, this kind of mental gymnastic doesn't happen on accident - it only happens to those who want to justify these things for some reason.
The main reason is reactance bias. Libertarians spend a lot of time focusing on the authoritarian left, but there's also an important element of reactance bias against the libertarian left. In my experience, ancaps who succumb to the alt-right infection always get one interesting thing right that less corrupted ancaps usually don't: their perspective on violence against the state. One of the main reasons I loved Nullus Maximus so much before I learned he was a fascist is his brilliant articles on revolution. Christopher Cantwell wrote something similar, and I believe Michael Malice is known for it too.
Now here's where it gets darker. Guess what happened to Christopher Cantwell? The FSP banned him. Not for being alt-right and supporting state aggression, not for being a bigot, but for thinking that self-defense is still valid against the government. How... can you possibly be a libertarian and disagree with that?!? (He was very clear that this was not a recommendation for the near future, it was a statement about ethical legitimacy.)
Nullus Maximus also wrote in his anti-border piece "There is almost a perfect overlap between libertarians who have come out in favor of importing Syrian refugees and libertarians who will denounce anyone who argues in favor of the use of defensive force against the state", linking the Cantwell story. Sadly, he's probably right.
The FSP and others who do this were wrong. Even if their opinion were correct, they were wrong to ban him. Libertarians have to be allowed to be wrong. You can't build a movement if you ostracize anyone who's wrong about something.
This is very important to talk about because it illuminates a partial solution to the alt-right pipeline. Cantwell and Maximus's descent into the alt-right were partly caused by this. For a right-libertarian, being ostracized by left-libertarians for being too libertarian is a critical blackpill. It teaches them that left-libertarians are not ultimately their allies. Libertarians and especially left-libertarians need to stop being wrong about this, or at least stop being so hostile to it as to refuse to even allow the discussion.
There was actually another issue like this that was huge in 2020: reaction to the draconion lockdowns that most governments enforced in the name of COVID-19. On the whole, right-libertarians were influenced by reactance bias toward downplaying COVID-19, but left-libertarians spent all their breath demonizing anyone who stood up to these lockdowns.
At the start of it, I expected left-libertarians to be on the right side. What I saw instead made me look back at people like Dave Smith and Austin Petersen and think, "you know, maybe these folks aren't so bad".
The C4SS author "Chris Cross Chaos" used to run the Twitter account @ileadliberty, whom I knew. @rechelon seemed to have cognitive dissonance, but @ileadliberty was very clear to me that not only did they hate anyone who protested against the COVID-19 lockdowns, but that they supported the use of coercion to enforce them. The only thing they didn't like about them was the lack of government handouts to go with them. So that's the kind of person who gets to publish in one of the most respected left-libertarian outlets, while I was rejected for retweeting posts questioning the severity of COVID-19 and pointing out verifiable media lies. We've got a problem.
This is not an attempt to absolve our alt-right former comrades of guilt. But we cannot afford to use someone else's flaws as an excuse to ignore our own. The above are grievous errors made by left-libertarians that have harmed our movement and contributed to the alt-right pipeline.