Okay, so you’re talking about an antisocial group that is attempting to prefigure a society of domination within the existing anarchist society.
Well, assuming they’ve established themselves as a continuing threat, the short answer is: violence. We use defensive violence against their encroachment until their group crumbles, which shouldn’t be hard since by definition most of their members are living a way worse life than they would without their oppressors, and they’re surrounded by examples of people living free.
Hierarchies are fragile. Also, in order to exist, an anarchist society has already solved the problem of how to keep hierarchies from forming.
The voluntary prison idea is a way of dealing with individuals, not organised groups. That’s an entirely different situation.
It makes sense if you think of them as extremely well-funded frat boys with a free pass to break laws.
They just kind of do shit, and if it doesn’t work they keep trying until something sticks or they run out of steam. They get killed all the time.
It’s still scary, but just a lot less cool.
The reason we think of them as hypercompetent masters of espionage is because that makes better movies, and also because the US government funds movies that make them look good.