The idea behind mensa is that people with high IQ's need to associate with their own kind to feel comfortable. This is elitist crap. People who are truly intelligent are able to effectively communicate with the largest variety of people. In fact I would define that as a dimension of intelligence.
I once had a girlfriend who had joined Mensa to meet "smart guys". She said all she ever met were geeks and ADD freaks. Then she ended up with me. </irony>
Well, you can call me an elitist (though I've never been a member of or interested in Mensa), but I don't think this is crap. Happiest times of my life were when I was among high concentrations of intelligent people on a daily basis.
The very existence of this community is evidence against your point. Or are all the truly intelligent people out there happily communicating with YouTube commenters?
Are you sure that you were happy because the people around you were intelligent? Or was it because you were in an intellectual environment where people discussed interesting topics?*