IQ seems to be more predictive at the low end than the high end. Someone with an IQ of 60 is handicapped. Someone with an IQ of 100 is normal. Above 100 the differences start to vanish into noise due to loads of other confounding factors and random chance.
I have taken several tests in my life. They have all shown above average but the differences have varied wildly from 120 all the way up to 160 or something. That is a crazy variance and really makes me feel like the high numbers are hand wavey BS.
The same is true of lots of other biological metrics. Very high cholesterol can indicate a problem. From the normal range down it's not predictive of much unless it is absurdly low. Low IQ probably indicates a neurological problem. Normal and above is... normal.
The "IQ cult" is bullshit. It seems like compensatory narcissism to me, like people who are fairly intelligent trying to clutch IQ because they are not in fact super successful. They are trying to rationalize the fact that high IQ does not automatically translate to better outcomes and many other factors dominate once your IQ hits the normal range.
The IQ cult is also deeply anti-intellectual. It neglects the value of ideas entirely. Who would you bet on? A person with a normal 100 IQ with sane rational beliefs and habits of thought or a person with a really high score whose mind is full of loony garbage? Having a big engine in the car doesn't mean anything if the driver is bad. Some of the nuttiest people I have ever met would undoubtedly get a high IQ score.
You can see a good A/B experiment on IQ vs ideas by searching for photos of North and South Korea from space. There is basically no genetic difference at all there. The difference is 100% ideas.
My personal observation is that in the realm of neurological factors motivation and focus are more important in terms of outcome than IQ beyond the normal range. I would definitely be tempted to exchange some IQ points for the dopamine system that super successful people seem to have.