I was invited to join MENSA in 1976 after I got my Army ASVAB GT score of 148 (local recruiter said that was the second highest score he’d ever seen, first being my brother three years earlier, had a draft # of ONE right when the little dustup in VN was called off). So my first permanent duty station, Monterey chapter said to add ten points to get a rough IQ score. Sure. So I joined. Paid a few bucks’ worth of dues, went to a couple meetings. Mostly D&D and SFF discussions. The single most boring, arrogantly entitled, cluster “F” of effete snobs and geeks I would never want to be associated with again in this lifetime. But it looked good on my college and med school applications and CV for future jobs; Phi Beta Kappa got more notice.
I visited a local chess club, what I would depict as a close approximation of what a Mensa meeting would be, and I got the exact same whiff of snobbery that you mention. I played one of the best guys at the table just for fun. I lost, but made some moves that really put him in a spot. I never went back, even though I craved some competition playing the game. No one in my immediate circle or family play.