I completely disagree with you. To immediately jump to this conclusion without performing a proper psychological evaluation of the person in question, which you obviously did not do as some rando on the Internet, is silly.
When I was a kid, I hacked my school computer network. Didn’t mean I had a mental disorder. I was a smart kid, school was easy so it was a challenge (I wrote my own DLL in C as a key logger installed from VBA in Excel), fun project with a friend, a thrill. I did a prank of making the OK button on the login screen run away from the mouse, similar to (based on the limited information Eugene revealed) what I presume happened here of a CSS hack to hide the leave group button. I don’t know what other more malicious things this person did, but immaturity and retaliation against a perceived injustice are natural human emotions, not indicative of a mental disorder.
