[livi]

Aggression stems from fear. Fear stems from low self esteem. Low self esteem stems from a combination of inherited personality traits and upbringing, traumatic experiences etc. On top of that it might be complicated with mental disturbance or disease.

Either way this guy is hurting. Plausibly enough to be a danger to himself and others. Unfortunately he is unlikely to fully recognize it himself - but he needs help. Professionally. Generally speaking.