The article is talking about people who drop out of school or don't go to college in the first place, and can't hold down a job. 82% of Mensa members have a four-year degree, and their median income is above average. Their demographic is clearly not concentrated on people like this. I'm sure many of their members have unfulfilling jobs or unfulfilling lives, as is the case with many people in general, but that's a different thing entirely.

(I feel like I should clarify that I'm not a Mensa member and don't really care about the organization one way or another. I was just curious about the initial claim and looked up the basic membership demographics.)