It was, on occasion, hilarious.And how is this different from being a mundane warlord? It isn't like the Roman Generals assassinated the Emperor so often because they found it funny.
Mutually assured destruction.Whenever someone gets power, others will put themselves against them to take that power.
There's never a winner. Just gridlock ad a lot of funny old men in increasingly elaborate hats kill and get killed.You proposition seems to assume that no magi could gain power, because other magi would tear them down.... but wouldn't the winner of a magi vs magi fight to determine who is in charge end with a magi in charge?
Vallcorp International is not responsible for lack of imagination in the PHB. The antimatter rifle in the DMG will have to do.I also don't see the rocket launcher on the PHB inventory. Could you tell me which page you are pulling that from and how the common people of a kingdom somehow all have rocket launchers that only work against magi, and that magi can't use, to allow the muggles to be the ones who rule?