When I was 18, my high school girlfriend took me to the local Mensa chapter’s New Year’s party because her mother was a member and she was used to hanging out there.
It was a useful lesson that whatever IQ tests measure, it is completely devoid of value or interest to me.
At the risk of sounding like one of those people at Mensa that annoyed you...
The people at Mensa aren't a valid sample of people who score high on IQ tests, because there is a such a strong selection effect for people with certain personality traits, such as wanting to join a club based on your IQ.
Or, to put it as Groucho Marx did:
"Please accept my resignation, I don't want to belong to any club that would have me as a member".
https://www.youtube.com/watch?v=kJHUres_2xU&t=228s
By looking at interactions of people in Mensa I feel like 2% of top IQ is actually too low bar to notice anything particular about "high" IQ people. We are still pretty random in our interests and performance.
To be fair, Mensa is a Venn diagram between IQ and being a douche.
I suspect my IQ isn’t quite high enough to join Mensa but I’ve always flirted with the idea of trying to join and getting in just to see what a group of Mensa people are like.
We are basically random. 2% of population by top IQ test result has pretty much very similar distribution in all aspects to 100% of the population. It's not a high bar to be fastest processing one among 50 people.
What does having value or interest to you have to do with intelligence?
What does IQ have to do with intelligence?
(Please forgive the flippant response. I believe it cuts to the core of what the parent was intending.)
Is it a serious question? IQ tries to quantify the positive correlation between the results of all intellectual tasks a person takes (AKA positive manifold).
Whatever the people who came up with IQ intended isn’t really relevant to the question of whether IQ measures intellect. At best is is loosely correlated. Very loosely.
OK. Demonstrate it. BTW, you can easily read critiques of "The mismeasure of Man" if you want to.
IQ strongly correlates with many real world outcomes that people tend to associate with being more "intellectual".
IQ has precise definition. It's what the tests measure. Intellect has only fuzzy handwavey definition. Correlation between IQ and intellect is about as loose as the definition of the intellect. The way people make the correlation even looser is by defining intellect in even more fuzzy and nebulous manner.