Video games are not a medium to judge character from.
You can very well judge a person by their intent, though. Somebody who seeks to create grief and displeasure for others is not affecting a "grief stat" in a video game, they are doing their best to create real frustration in another human being.
"Displeasure of others = Amusement" is an equation adhered to by those who thrive on their anonymity of the internet. We are defined by how we act when nobody is looking, and anonymity of the internet has none looking at you.
You can't diagnose a mental condition through a game interaction, but it's still their chosen behavior.