I had another friend who read the book. I remember him finishing the book as we were on AOL instant messenger. He like, yep, that ended how I was thinking it was going to....but he didn't tell me what it was. He was a pretty clever guy.
So yeah, when I did see it in theaters, and working at the theater during those years, was able to get me and another friend in for free. We were totally blown away by that ending......and now looks like we're all blown away by more meaning of the whole movie.
You could almost expect to find him in a mental hospital strapped to a bed and envisioned all the events of the movie completely in his head with this type of reveal. Not that thats how it happened, but its some pretty deep stuff.