Depending on the event, showing up without doing an RSVP can be worse than not coming. I think generally it depends on whether the RSVP is being relied on for s

Depending on the event, showing up without doing an RSVP can be worse than not coming. I think generally it depends on whether the RSVP is being relied on for something, for example an accurate headcount for a restaurant reservation. For a regular meetup, it's not nearly as important to RSVP. Maybe even overly formal. I go to a weekly thing that's organized through Meetup, and I still RSVP every time, though, for a few reasons. One is it puts it on my calendar automatically. Two is it helps newbies feel comfortable that somebody is going and they won't be the only one there if they show up.