You have a kid that grew up thinking (not without a reason) that there's no better way than that do what the boss says. It will die to protect him. "Oh that kid is just a criminal, kill him!". In many cases, places where these cartels thrive are places where they locally can do better job than the government does.
I don't think that taking out the highest figure simply solves the problem. It wouldn't change much on the long run and on the short run highly increase the violence.
But more importantly, it seems extremely rare, that you could make a world a better place simply by killing somebody or a bunch of people. It's easy to think that, and a HN comment is too short to dive into that, but when you take time to think everything through, it seems far from obvious.
Your confidence that you'd sacrifice yourself heroically in circumstances it's utterly certain you'll never find yourself in is admirable.
Well not kill myself for a start...