Equating people experiencing depression with those who have violent delusions and borderline tendencies creates a worse stigma on seeking treatment than recognizing that dangerous people are just plain dangerous. Sure, we're all people etc, but in an emergency, there are men and women you can trust, and there are ones you can't. A psycho is someone who threatens or harms others for gratification, and it is an epithet they earn. If that's "prejudiced," perhaps we're just from different cultures.
The stakes change when there was a reasonable threat that their actions could put people and their families at risk.
Obviously the etymology of the term comes from psychological illness via a certain famous Hitchhock movie, and that's one reason why the term du jour these days is "Karen" instead.