In most Star Wars game (as NPC Brown Cow has already said), you become an NPC. In the latest Star Wars game (FFG's), you don't but you quickly go darkside and aren't a Jedi anymore....and the setting is just fine. The Star Wars universe is full of fallen Jedi with ideas very much like this. The GM may not want to handle it, but the setting handles it just fine.Really, the problem there is that when many gamers hear their GM say "you can't play Dark Siders in this game; if your character falls to the Dark Side, he becomes an NPC, and you have to make a new character," what they say to themselves is, "Cool, I want to play a Dark Sider, so I'm calling the GM's bluff. He doesn't really have the stones to take my character away from me. Let's rock! I have to hurry up and fall to the Dark Side now so I can put the GM in his place by establishing dominance."