because it's been specifically engineered to get stuck in your head, and koreans have figured out how to deploy this engineering in a much stronger way than most western music. there's also a potential - 'spiritual' for lack of a better term - aspect. my reasoning for this is that korea has had a long history of strange occult shit going on. i'm not sure how many of you know this, but many people forgot after it hit mainstream news a few years ago that the south korean government and their leader was actually just a figurehead for an occult-oriented shadow government. (i think it was mostly made up of women.)