I have been a co-organizer, a core member of a very successful group, and a long-standing member of a few groups that I only occasionally frequent.

Meetup groups amplify the best and worst qualities of the people that organize them. It takes a strong core of regulars to establish a safe/inclusive environment for newbies and offload the event organizing work so the head doesn't burnout.

Usually groups fall apart when they lack a strong core or the core members start hooking up. Any negativity expressed by the 'regulars' will reverberate throughout the group and likely split its members into separate tribes.

You can usually tell which groups will fail within the first year by looking at the head and core members. If the head of the group makes it about 'me myself and I', or the core members fork off into exclusive side groups, the group will start to diverge at the first sign of conflict.

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As for the inactive members. They don't really matter in the long-run. Some groups wisely cull inactive members, others don't. For those that do, culling priority can be separated into 4 groups.

1. The Flakes

RSVP for multiple events but consistently don't show up. They probably have the right intentions but lack the followthrough. Unfortunately, they take up slots that would otherwise go to active members so they should be cut if they're consistently unreliable.

2. The Window Shoppers

Indistinguishable from the Lurkers. They join a group for the same reason guys indiscriminately swipe right on Tinder. They're a waste of space. If/when they do show up, there's usually some hidden motive. Ex show up because 'cute girls', get drunk, embarrass themselves, leave the group the next day. It's not a bad idea to cull them if the group is established and has a lot of members.

3. The Lurkers

Members who would really like to participate but are nervous about being out of their element and could use some welcoming encouragement. They're the sole reason why it's not always a good idea to cull suspect 'window shoppers'. It would be awesome if there were better tools to help get these members involved.

4. The Dalliers

Members who RSVP but only occasionally. I think most active members fall into this group. They haven't found a personal connection to the group for one reason or another so they only participate if the group is hosting an interesting event.

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In a lot of cases, it's not hard to tell which groups will overwhelmingly attract one (or more) of the 4 types above.

Any group that advertises 'partying', 'singles', 'nightlife', or 'dating' will overwhelmingly be dominated by flakes or window shoppers. The flakes mostly being women who want a B plan if their other plans fall through, the lurkers usually are guys on the hunt for some 'strange'.

Groups that advertise ideals like 'fitness', 'foreign language', 'book club', anything related to being 'active' will be dominated by window shoppers. These are things people 'would like to see themselves doing' but they won't join a group to do those things for the same reason they don't try to do them alone.

The vast majority of groups are dominated by Lurkers for the same reason dating apps are dominated by users who rarely (if ever) date anybody from the app IRL. There is no barrier to entry and most people are too chicken shit to step out of their comfort zone.

Some groups overwhelmingly attract Dalliers for a few reasons. There's no strong common interest. The events are consistently uninteresting. The group lacks a strong core. Some members participate but never found a personal connection with the group. Some groups host good events but are nothing but thinly veiled marketing/advertising platforms.

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I've been all 4 of these at one point or another. It all depends on the culture of the group. Being a core member of a really successful group was a hugely rewarding experience. I made a lot of friends, had a ton of great experiences I otherwise wouldn't have had on my own, and had an awesome time. I would do it again in a second if I could find another group worth the effort. Unfortunately, I moved to a different area that is dominated by a very superficial/materialistic culture and the Meetup groups mostly reflect that culture. People never drop their guard and 'be themselves' when they're constantly sizing up or being sized up by others in the group.

Meetup has always been made up of mostly lurkers and even more so as it grows in popularity. For every 1000 members a group has, maybe 100-150 are active members, and if lucky 10-50 are core members.

Statistically speaking, the inactive members are 'noise' so making assessments by numbers will likely produce meaningless results. In other words, garbage-in-garbage-out.