Unfortunately it's not so simple. You start out as a Chemistry teacher who just wants to make money on the side giving people a quality product, and end up committing multiple murders.
EDIT: I just read what you actually wrote. only killing people as needed??? You're nuts.
So it's quite understandable that a criminal organization might need to use force when someone threatens their safety. This happened for instance with the Silk Road, when someone blackmailed them. (Now, the SR shouldn't have allowed themselves into that position in the first place, but that aside). It's a "necessary" understandable case - if not taken care of, dozens or hundreds of people could be condemned.
Contrast with these cartels, which hijack passenger buses, then torture and rape for fun. There's no necessity there.
Do you not see the distinction?
This kind of behavior has had a strong appeal throughout history to many of those with the strength to carry it out without any real risk to themselves. See Jack London's "The Sea Wolf" for a great portrayal of the conflict between this mindset and our own. It's player-killing in video games in the real world and the only effective way to respond is with greater force.