Is a monopolist on law & order necessary? If so, how can you prevent anarcho-tyranny? Why do people follow laws anyway? If a private law society existed which laws would exist and how would such laws be enforced?

Is a monopolist on law & order necessary? If so, how can you prevent anarcho-tyranny? Why do people follow laws anyway? If a private law society existed which laws would exist and how would such laws be enforced?