My friends always say "You can't just kill them. There will be someone to take their place." The obvious response is kill them too. Eventually, people will stop being so eager to take their place!
Though as the comic says, there's always going to be assholes. Limiting how much power they have would be great.
I am currently running a game of Vampire predicated on "what if you all just.. took out the ultra rich?". It has been satisfying.