The people that would pay is those who want violence carried out against other people.
Imagine some of the people who would pay for violence, they do and then use that violence to steal silver. The silver is used to pay back the violence. These people's business can have a positive net income until they run out of people to prey on and then start attacking each other. That's basically the gist of ancient Roman history.
How can an economy without government prevent an despotism or oligarchy from emerging from within or from attacking from outside? I ponder this.