It started with an idea: "Planet Government".
Someone proposed, a couple of decades ago, that we find a dead world somewhere and let all the rulers and would-be rulers of the world emigrate there, along with all their militaries. And those who just can't get along with others.
Let them fight it out among themselves as much as they want, but warn them that if they ever return to Earth, they will be expected to abide by the Zero Aggression Principle and the Covenant of Unanimous Consent, and if they don't they will be subject to self-defensive actions. Just like any other thug. They will never again have a "position" or any veil of legitimacy to hide behind.
It wasn't an exile, but was completely voluntary. And, it was shocking how many jumped at the chance to live in a constant Hell of fighting and power struggles, rather than forgo getting what they wanted by coercion.
The authoritarian types were already becoming miserable here. Too much peace. Too few controls, and too little "crime". They had already lost power, and since that was all that gave their lives meaning, they chose to leave rather than adapt to a voluntary life.
It took several years, and a LOT of money, willingly donated, but it did happen. They launched long ago. The thing is, no one here knows if the ship ever made it to its destination or not. Their ship does have the capability to communicate with Earth, but no one was interested enough to monitor their progress.
I hope that whatever happened to them, they are happy. And I hope they never try to come back. But if they do, we are ready for them. Without their lingering influence, society is more "polite" than ever- by which I mean it is the rare individual who goes anywhere unarmed- almost everyone is ready to defend against theft or aggression. And there are anti-asteroid hobbyists who could deal effectively with the threat of an incoming hostile ship or missile.
Life is better here without them.