Most active clubs that have stuck around started as folks who were getting together regularly around a thing for long enough they decided to formalize it. The one exception was there was a freethinkers club that I think started as a guy putting a meetup notice at a restaurant for brunch for freethinkers at an establishment that had enough extra space and where fine with pushing tables together. When it got to big it started meeting at his home. I think he figured he would go for brunch and if people showed then bonus.