Would-be monopolists don't particularly enjoy playing by the rules of the game. To crib a quote, it becomes the art of saying "good free market" while you look for a stick.
If there's a state, it's natural to try to corrupt it to use its political power. If there is no state or that option looks unappealing, the alternative is to get some political power of the sort that grows out of the barrel of a gun, i.e. to be organized crime.
The implication of the question, that the state is necessary to produce a monopoly, fails to give the full picture. It's not as much that the state is necessary, that economic power can eventually be translated into enough force to subvert the rules. In the absence of a state, that force just takes the shape of an authoritarian proto-state, itself.
If there's a state, it's natural to try to corrupt it to use its political power. If there is no state or that option looks unappealing, the alternative is to get some political power of the sort that grows out of the barrel of a gun, i.e. to be organized crime.
The implication of the question, that the state is necessary to produce a monopoly, fails to give the full picture. It's not as much that the state is necessary, that economic power can eventually be translated into enough force to subvert the rules. In the absence of a state, that force just takes the shape of an authoritarian proto-state, itself.