"American Psycho" begins with the usual disclaimer. "This is a work of fiction. All of the characters...are imaginary and are not intended to refer to any living persons..." I should hope not.
It is rare to read a book cover to cover when you cannot stomach any aspect of any of the characters. They are ALL hate-worthy. Not even the fact that the main character (hero? anti-hero?) is a serial killer is endearing. They are all pompous, self-centered idiots.
So, what would keep a reader reading a book populated by such people? Patrick Bateman's descent into madness. What a spiral. What commentary on society that his behavior could go completely ignored. What a fun ride!