He intended The Collector to be a commentary on class, not psychopathy.
psychopathy, more or less, is the clinical term for sociopathy, and the two are often used interchangeably.
One can almost envision a dark party game that involves ranking our favorite historical figures on a scale of psychopathy.
psychopathy psy·chop·a·thy (sī-kŏp'ə-thē)
Mental disorder, especially when manifested by antisocial behavior.