Why is the Death Penalty still allowed if it is really expensive and unprofitable?

I want to steal things. I want to kill people. I want to cut people off in traffic and run over bicycles. Get the fuck out of my way, right? But you know what? I control myself. I follow the rules. But when I see someone stealing, or who cuts me off, I get so fucking angry, man. Why should they get away with it? I'm sitting here doing everything right and all I get from it is shit. So why the fuck shouldn't I just steal shit and kill people if you can just get away with it? Society only works if there's punishment. Don't let your fucking dog shit on my lawn and not pick it up. God dammit. Just fucking behave. It makes me so fucking angry. I wish I could punish these people myself. So many people do bad things and get away with it. There are people who follow the rules and people who don't. I see someone who doesn't follow the rules. I'm so angry. We need more good people and less bad people. Society won't work like this. My fucking hands are shaking man I get so worked up when I think about it. You can't let them get away with it. They need to be punished more severely, obviously. We need to catch all of them. Until it sinks in. Until the bad people are gone or stop being bad.