[xg15]

It's trite, but I think a part of it is "because the internet happened" - and I don't mean just today's enshittification era but also the "good old times" everyone seems to remember fondly here. At some point, the internet was full of that kind of community spirit that you described, but of course this meant that people were more likely to direct their energy to online community building than to real-life stuff. And unfortunately online communities didn't always teach the skills that offline communities required, and also probably contributed a lot to the "consumer mindset" the OP warns against...

[danaris]

As someone who was growing up during the period where the Internet became mainstream...

This was happening before then. The Lions, Rotary, etc clubs in my area made very little effort to reach out and invite younger members. Aside from the Rotary exchange program, I couldn't have named a single event they were putting on that was genuinely aimed at people under the age of 50.

And the few times that they did try to talk to some of us young people about the club, the very, very strong impression I got of the pitch was "you can pay significant monthly dues to come to meetings with old people and occasionally go do volunteer activities out in the community." I already did some volunteering without having to pay for the privilege, and I didn't see the draw of going to meetings with old people.

[ghaff]

I suspect there are a lot of reasons. You don't have men and their housewife for the most part. So the typically male Lions, Elks, etc. clubs don't fit as well with modern lifestyles for that reason in part. Bowling nights went out of fashion. People are less likely to to be clustered in a town/small city for work. There are just a lot of reasons why routinely heading down to $PLACE with all the guys after work just isn't that popular any longer.

[Exoristos]

The downfall of social institutions was well on its way by the Boomers.