Be very careful which groups you join & scrutinize the intentions of the organizers.
In general, the organizers exist to serve their own interests. I have first hand knowledge of one organizer who's created various singles clubs to target the age groups of twenties, thirties, fourties, fifties. He also used fake personas of pretty girls as co-organizers, to kickoff invite to meetups. Now approach a venue / restaurant and offer to bring X people if they can give you a kickback. The kickback varied from negotiating a cheap meal (and not passing it on, in effect pocketing the difference). Needless to say, the pretty organizers always found an emergency excuse not to turn up. This happened in Sydney Australia. Thread very carefully if you live in Sydney and see variations of the same theme, do not take anything at face value.