is one of the most common responses I get when I talk to people (usually liberals) about horizontal power structures. It comes down to some version of "Well, that sounds nice, but what about the bad actors?" I think the logic that follows from that fact is backwards. The standard response to this issue is to build vertical power structures. To appoint a ruling class that can supposedly "manage" the bad actors. But this ignores the obvious: vertical power structures are magnets for narcissists. They don’t neutralize those people. They empower them. They give them legitimacy and insulation from consequences. They concentrate power precisely where it’s most dangerous. Horizontal societies have always had ways of handling antisocial behavior. (Highly recommend Hierarchy in the Forest: The Evolution of Egalitarian Behavior by Christopher Boehm. He studied hundreds of forager societies, overall done amazing work.) Exile, public shaming, revocable leadership, and distributed decision-making all worked and often worked better than what we do now. Pre-civilized societies didn’t let power-hungry individuals take over. They stopped them. We used to know how to deal with bad actors. The idea of a "power vacuum" only makes sense if you believe power must be held at the top. If you diffuse power horizontally, there is no vacuum to fill. There’s just shared responsibility. That may feel unfamiliar, but it’s not impossible. We’ve done it before. Most of human history was built on it. The real question isn't whether bad actors exist. It's how we choose to deal with them. Do we build systems that make it harder for them to dominate others, or ones that practically roll out the red carpet? I think this opens up a more useful conversation.
What if we started seriously discussing tactics for dealing with domination-seeking behavior?
What mechanisms help us identify and isolate that kind of behavior without reproducing the same old coercive structures?
How do we build systems that are resilient to sabotage without falling into authoritarian logic?
I’d love to hear your guys’ thoughts.

Are there examples of stable horizontal power structures beyond ~1000 people?
Some examples of large scale cooperation without authority or hierarchy are Bitcoin users/miners, sci-hub, historic communities in Spain and eastern Europe and French communes, modern autonomous zones in several countries like Mexico and France where law enforcement will not go.
Another idea is that even in a place where authority is centralized under a hierarchy of power, that power only exists temporarily when it is enforced and anarchy rules apply until the power is enforced, i.e. laws of any system only matter when they are exercised. Anywhere considered wilderness or frequently autonomous without law enforcement access would fit this category.
Good examples, especially that last idea. I will say Bitcoin mining certainly doesn't count though, there's no non-hierarchical cooperation since everything is enforced by the rules of the system they're using. Possible attacks that work despite that system, eg. a majority consensus attack, have been tried on blockchains when they might work.