ok, i didn't get that from your post. most groups you mention as example are not in that category. except for religious groups (and cults with are a subset of religious groups) none of the groups have any expectation to last. so i don't quite get what your point is.

you argue that the fate of groups is to end when leaders stop putting effort, which is kind of self evident unless there is an underlying premise that is able to outlast the individual groups. my group was effectively dead before i took over. i rebuilt it almost from scratch. that was only possible because it was based on an underlying idea that others could identify with that was not dependent on my person. FOSS groups come and go but the FOSS community as a whole won't ever die. same goes for religion. at least the kind of religion that is based on written word.

why is a 75 year old organization not old enough? given that members can join at most 15 years, that's already 5 generations.

you also argue that the only thing that makes groups last is money or social status. if that were the case most groups would not even start.

i understand your personal experience, and that's fine, but that has nothing to do with multi generational organizations. it seems to me that you are mixing two unrelated things here.