Some people don't have anything else to offer to get attention so they settle for negative attention and call it "being tough." Compensation for lack of knowledge by trying to look superior.
A sad thing and painfully true in RL. It's expected for some young people. They may have never been cared about enough to be taught better. They have lots to learn yet before they have something useful to contribute. If they don't learn something along the way it looks pretty pathetic as one "matures."
Some feel a need to "punish" others for the hand life has dealt them. It's a self-perpetuating cycle of abuse. Wounded egos make for pretty miserable companions.
Other posters may be struggling with mood or thought disorders and not attending to their health.
If it's small consolation, their lives are much more miserable for them to live then it is for others to watch.
It grieves me to know something they don't. All they need to do is take a cue from those around them and do the hard work it takes to enter the society which they choose to distain because they don't know how to enter it.
Lonely, frustrated, angry, hurt. Tough way to live a life. And a poor decision not to try to change that.