To be honest I seriously have zero sympathy for teenagers who cut and think it's cool.
Why don't you have sympathy for teenagers that self-harm?
They are spoiled brats.
Teenagers that self-harm by cutting themselves are likely going through a difficult time. It's best to put yourself in their shoes for a while and then reconsider how you feel about them.
I wouldn't have done it to myself though. I was telling them to stop.
For something as terrible as cutting, telling them to stop isn't enough because it's just words to them. Those teenagers are likely in need of extra assistance that is based on action rather than words. At the end of the day, it's difficult to understand why some kids cut themselves, and the only thing you can do is get them connected to a therapist to help them recover.