Both the book and the movie are fake. Come on, the chainsaw scene? The killing spree scene (Chase, Manhattan in the book, which is in some ways more ridiculous)? He shoots a cop car twice and it explodes. Feed me a kitten, and a kitten happens to be right there? The most telling thing of the movie, and people seem to ignore this, is that there are two cuts of him walking into his lobby, one with him killing the person at the desk, the other with him frantically getting into the elevator without the murdering. The second, non-killing cut, is him waking from his fantasy: none of the shit happened, but he thought it did.
It is even more obvious in the book. In the aforementioned, notorious Chase Manhattan scene, the narrative slips from first to third person, indicating that this is not happening, but Patrick himself is envisioning it happening. Another key giveaways in the book include the ridiculous scene where he kills a child at the zoo. Most telling is the book's buildup. In the book, not only is it a very long time before we see Patrick do something crazy, it's also quite a bit before we even hear him say or think something psycho-y. Sometimes he says something that can be taken as creepy, but nothing your average Joe hasn't said when dealing with people he dislikes.
