The criminals shooting at each other weekly where I live are all 18-25yr old drug delivery drivers working for established bosses they clearly aren't rational or else they'd realize a few thousand a week isn't worth life in prison. Plenty of these guys get caught but there doesn't seem to be any shortage of violent replacements.
Actually, they are pretty rational. You can't say no to the boss. You say no to the boss, you die. So they either deliver that drug, or die. They choose to deliver the drug, even if it means getting caught and doing life in prison. That's better than the boss killing you for not delivering the drug.
>The criminals shooting at each other weekly...
Again, they're not being irrational here. If you don't shoot, the other guy will shoot you. You either shoot, or you die because the other guy shoots you.
The yakuza basically never carry guns around anymore because the charges for carrying around a handgun are so high that it's just not worth it.
We always say that "well if someone wants a gun they're gonna get it", which is pretty true. But some deterrents can slow down the transition from " I don't like that guy" to "I'm going to kill him" (hell, if we stop at "going to beat him with a bat", that's still a bit better).
People aren't rational, but things like advertising works, so some form of deterrents must work too I think.