Disagree. You can't just up and leave when you want to.Ego. Thinking they're untouchable.
You are making a VERY powerful criminal/crime syndicate MILLIONS UPON MILLIONS A YEAR. You simply cannot go "well Mr *insert drug lord's name here* I've made my $10 million, I'm retiring. Bye!". You are making too much money for too many powerful people for you to just stop. Because it's one hell of a domino effect if you do on both sides.
Ego does come into it, but it's not like a 9-5. Your time ends when the wheels fall off. And if that's when YOU get caught, your supplier gets caught or for a different reason then so be it. But to think you can simply walk away is at best laughable.