While there is definite truth that paying even $1 to RSVP for an event cuts RSVP no-shows significantly, I don't see this flying when members of meetups are acc

While there is definite truth that paying even $1 to RSVP for an event cuts RSVP no-shows significantly, I don't see this flying when members of meetups are accustomed to paying exactly ZERO to attend events. If there isn't an open source alternative to meetup.com now would be the time to create one, and if you want to create The Winner then have your meetup replacement able to federate with other (using ActivityPub?) to replace the "members of this group also join these groups" network effect that makes meetup.com so popular.