I began cutting at thirteen, burned for the first time at 14. Didn't burn again until I was 15. Did both up until I was 25. I self harmed for a long ass time. On the day of my last relapse, I hadn't self harmed in a year.
Endorphins end all pain, including the emotional. Replace that pain with emotional pain and it goes away much quicker than your emotional pain would, and that emotional pain is gone because you cancelled it out. Self hated and the belief you deserve it helps fuel it. If you can't feel from anything else (especially if you struggle with anhedonia or feeling numb/empty), pain wakes you up. It becomes addicting, that release. You feel bad ass and rebellious and cool for being able to withstand the pain. Rinse repeat.
Those emotions getting stronger and stronger because you're avoiding them, not facing them. As a result, you cut more and more.
I quit because it just doesn't do what it used to do for me in the past. I didn't try to stop. I just did. I'd rather get drunk these days
Sometimes people would rather feel physical pain than emotional pain. That's where I was at.
Also I think self harmers prefer to take their frustration out on themselves rather than others. That was another motivation for me when I was young.