when you're fighting through billionaire-owned militias

That's what the state is.

Radical social change is always difficult. But if you’re implying that authoritarianism is more effective at defeating capitalism, I disagree, and I think there’s strong evidence from history that undermines such a hypothesis.

That said, I think for anarchism to succeed there does need to be a sort of balance and destructive competition between the existing powers of the state and private ownership (or foreign states as we see in Rojava). Anarchists should observe and act with this dynamic in mind to prevent the total domination of any one structure over society, as this will be much more difficult to overcome. But eventually the goal is to build social power that is greater than either of them put together.