A lot of the societies are also not as well-attended as people would have you think. Even some of the more (in)famous ones are now down to only a few members, like the Bullingdons, who last time I heard were down to about five members (no-one can be bothered to buy the blue tail-coats, and getting your room trashed is a great annoyance). Many of the less well known ones have effectively become mere reasons for one prominent and rich member to invite a lot of other people he likes to a pretentious dinner.
And the sexuality ones aren't very popular now. Now that there's no need to demand secrecy, we all tend to go to clubs instead.