I’ve always thought the murders really happened. I think people miss the point of the final scene. It’s not that Bateman isn’t a murderer, he is, but It. Doesn’t. Matter.

Due to the vapid, superficial world he lives in No. One. Cares. No one cares if he’s Paul or Patrick or Whomever, everyone is interchangeable. No one cares if he’s a psychopath, he’s young and attractive and rich, so they don’t care. He’s literally been saying psychopathic shit for the entire novel, no one cares. His own lawyer laughs off his murder confession. The realtor covers for him for her own gain. The police are never going to arrest him, not even if he murders someone right in front of them. So there really is No Exit for him, he’s stuck, as a terrible person surrounded by terrible people. He’s in hell.

That’s how I always read it anyways.