Well to be fair, those are the subset of high IQ people who have the time/desire to join a club about having a high IQ. Kind of an adverse selection bias

The overwhelming majority of the high IQ are not Mensa members. They are academics, doctors, lawyers, successful businesspeople, the kinds of people for whom it is more common in their friends group to have a Master’s degree than to be a high school dropout.

Some people consider a person with a Master's degree to be a dropout. (yes, I know, not necessarily...)

Those people are called academics. The kinds of Master’s degrees that are rent seeking credentialism, MBAs, MSWs, M.Ed.s are far more common than consolation prizes for those who didn’t get their Ph.D.

Perhaps, but the context I heard it in was self-deprecating from someone working in industry, relative to engineers with PhDs.