> the history of the world is full of examples
The written history, the recent past. We can observe settlements from the past but know very little about the time before farming because there were few or no settlements, which is not actually that long ago. This "will to use violence use it for their own ends, form gangs, and militias" might only be because we ran out of resources and space and shifted from "mother earth provides" to "this is mine". At least, that's what a book I'm reading hints at, but again, it acknowledges very strongly just how little we know.
There isn't a going back to before possessions, obviously, but I'm also not convinced that a majority of us are dishonest by nature. Certainly enough that we need laws and enforcement, but what would happen if we manage to get to a point where there are enough resources for everyone and automatic systems do most of the necessary work like making food? Do we still need the same level of security just to protect ourselves from a few sadists or could we have a more anarchistic society? Can we embrace some of the ideas that those unhappy with our current society propose?
Honestly I feel like most of this discussion is a definition issue. One person will say "anarchism is great" or "that isn't what anarchism is, you have to picture it this other great way" whereas another will make different assumptions and conclude it's ridiculous. It's a bit like being in a communistic country talking about switching to capitalism and arguing that human nature's greed can't be trusted or something. Rather, it might make more sense to propose incremental changes rather than talk about a completely different society where (if we're all being honest) nobody really has any friggin' clue if it'll increase median happiness.
One thing that is clear from history is that forming groups is bad. Making this about us vs them (anarchists vs ), left versus right, etc.) inherently causes disagreement when I think most everyone's goal is increasing the common good.