This is the best comment about meetups of all time
One thing I found strange about SF is that I never found a group that would do the weekly hang.
The weekly hang is a socially porous experience, it has a fixed location and fixed start time but everything else is improvised. Different people could dip in and out, people felt free to bring new friends, people they just started dating, friends from out of town etc. Some people came once and never again, others become regulars. The hallmark of a great weekly hang is that the entire initial cohort gets replaced but the weekly hang still persists.
It's a commitment in time that "busy professionals" ostensibly had no time for which is why I think it was so unpopular in SF but it really killed a big part of the vibe of the city for me.
https://news.ycombinator.com/item?id=35608965