On top of everything else that was really wrong with that bastard Cho Seung-Hui , apparently was suffering from a delusion of being Oldboy.
Of course, Oldboy had the excuse of being taken away from his wife and child and locked in a room for years without any explanation whatsoever. Unless Cho spent some time we don't know about in Gitmo, all he had to blame was angst.
Update: Looks like someone at the NYT beat me to this observation. The article mentions an excerpt from the NYT review at the time of it's release and how such a film only appealed to "cult-film aficionados for whom distinctions between high art and low are unknown, unrecognized and certainly unwelcome".
Bite me, NYT. The current Tomatometer rating for Oldboy is 81% fresh, meaning that there were a hell of a lot of critics (who did know the difference between High art and Low) that saw it for what it was: a beautifully crafted film and moving film. Don't start demonizing this film because some schmuck got off on the violence and ignored everything else.