Interesting, but I have another potential theory. In the past, everyone was expected to love clubbing and partying. "Be there or be square," and square meant "loser." Now that introverts have stood up for ourselves, we no longer feel the need to hide our temperment. Partying may be great for some, but please stop painting us all with that brush. Those of us who are much happier at home with our books, our movies, our hobbies and our cats are not buying that propaganda anymore. Maybe this accounts for the decline in clubbing.