Psychosis and psychopathy are distinct, for what it's worth.
Drug abuse, criminality, and to a lesser extent - sheer failure at something, also lead to this framework. I failed this class because the education system sucks, I’m burnt out at work because my company sucks, etc. It’s so difficult to explain what’s happening, but somehow, across a variety of circumstances and pathologies, a similar framework emerges.
It’s curiously a human crutch.
I don’t envy shrinks, as they are confronted by the same framework by wildly different psychological explanations. And, it’s there job to find the dangerous ones that show up, needles in the haystack.
Symptomatically, personality disorders are basically relational dysfunctions. Some are developed as compensations for barely having an ego at all. They're fairly well documented.
The most shocking thing for outsiders is realising how alien they are. People with no knowledge of psychology literally cannot imagine how it's possible for people with these issues to lie consistently without guilt, act without empathy, and have conversations that appear coherent but make no sense at all relationally.
Drug abuse is a different issue with a much wider range of causes.
Burn out and educational failures are real issues and can be caused by real external problems. Someone who has a poor teacher objectively, or even just a teacher who is a bad fit, does not have the same psychology as someone who persuades themselves all teachers are bad because teaching itself is evil.
You can't dehumanize someone and claim to understand them simultaneously. It's logically incoherent to draw a conclusion from a failure to understand.
When I try to understand people, I start by assuming that they, like everyone, have an inner self with the golden rule hardwired at a very basic level, and anything appearing to violate that is an illusion creating by coping behavior, distortions in perceptions, or something. Psychic pain being prioritized over everything else can make the resulting behavior very confusing.
Also, since I'm not a professional psychologist I don't have to pretend I understand when I don't.