It is true that for capitalism to exist individual rights must be protected. It is not true that such protection can only be provided by a government.
Suggest OP reads For a New Liberty by Rothbard.
I thought for a long time that landowners might form de facto states too, band together, etc. But such would require aggression, and could be legitimately and legally opposed in such a society. Each man is a sovereign in a free society, but they would be unable to become a sovereign over any other man.
One man could subject himself to another voluntarily, but the minute that consent was removed he’d have a problem and would not be able to remain a sovereign over another. Thus, it would not be sovereignty at all, but license, and license can never become a right unless that right is voluntarily granted (which in the case of owning a person, can never happen, but license over goods could become right if purchased or given).
The real problem for a free society is how to deal with the person that, in the face of a crisis, stands up and screams, “Someone has got to do something!” It’s this sentiment that has resulted in states in the past, imo.
There has got to be a free-market answer for that person compelling enough to ignore any aggressive solution.
I think we do have those solutions and could make a stable free state. We would do it with voluntary subscriptions, with protection services and the like, and ad hoc corporations to achieve specific goals.
Need a bridge built? Get together an ad hoc group, form a corporation on the spot with all concerned people as members, put up money and solicit investment to complete the bridge. Once complete, those who financed and supported the project can even earn fees from the new successful bridge.
Now -that- is how we can replace and supersede everything that government is and does.