I’ve been involved in a number of clubs and classes since University, and in recent years I’ve been witness to the clubs that kids of my friends and family attend. In most cases, they follow a similar pattern. There are a very small number of highly motivated people who keep the club functioning. A slightly larger number of people who hang around in the periphery, stepping in from time to time to help out, but shying away from any formal commitment. Finally you have the vast majority of people who do nothing but drop off their kids and let them get on with it.
I’m sure you’ve seen a similar pattern yourself in clubs, online communities and even in companies you’ve worked for.