Meetup.com was a good idea, but I found them to be useless.
Here's my experience:
I was interested in hosting local meetups for techhies. I wanted to do it around Swift, so I knew there wouldn't be many of us.
Meetup had two "paid" tiers. One, was up to about 20 people per meetup, and the other (more money), was for an unlimited number.
Since I knew the meetups would be small, I opted for the cheaper one. I didn't expect more than five or six people at any meetup.
Once I started posting meetups, though, I started getting a lot of bogus signups. They were clearly bogus, as many had nothing to do with tech, or were unreasonably far away (like New Jersey or Upstate). I suspect most, if not all, were fake profiles.
These signups filled the meetups, so I would get like, one real person showing up. All the rest were no-shows.
Coincidentally (I'm sure), I started getting a lot of upselling contacts, recommending that I get the unlimited plan, as my meetups were so popular.
After a couple of these, I figured out which way the wind was blowing (straight across the cow manure), and dumped Meetup.com.