American Psycho was the book that got Brett Easton Ellis kicked off of Doubleday, as I recall.
Here's the thing: it's vapid. It's a vapid book by a vapid man about a vapid culture. There's a lot of shock bullshit in it but it's shock bullshit. There are no great truths in American Psycho beyond "we don't really know each other" which is pretty much every book Ellis has ever written.
If Stephen King had never met a human before, and didn't care to, American Psycho is the book he'd write.