Three insight into this movie and its hero--Bateman --from the relationship between one and society, others and himself.
Bateman is indeed driven to crazy by society oriented by secularity. He has good aesthetic for music, painting, dressing… they are totally fine but are distorted by commonplace mind from outside and crazy pursuits inside which finally make it sick without beauty anymore. His is being flushed away from himself by the trend as he is unable to escape from his wife's buzzing to place with music.
In his relationship with others, he is jealous of those who are "better" or "more identifiable "than him. Music and aesthetics doesn't help him become unique like Alex in clockwork orange but tags him as "successful "and the same with others. The more he do the more common he becomes. Repeating the everyday routine: Talking about politics, chatting with beauty, trying to reserving a seat and keeping fit, blind him of true love from his secretary.
For himself, just as the last scene containing homage to NO EXIT, he can't escape from the room of life and achieve his identity through that door. Confession of himself as a sick man provide no catharsis but make him a total ordinary man. To gain identity again, what he need is not confession but escape.