I think their market has stopped growing. At one time I'd monitor about 20 local meetups, half in computers, half in hobbies. But 80% havent had meeting since last summer snd are zombies.

I attribute these to a variety of issues. Sometimes they exhaust the local experts in a subject and runs out of topics. sometime its hot new technology that is no longer hot anymore and interest is in the next shiny object. Some meetups are tightly run by an individual and fade when leader runs out of energy, changes a job, etc. Maybe finances too in gathering $300 annual fee to buy a meetup topic.