Pegging success solely to income is disingenuous. It's not the only measure of success, let alone the only "real and hard measure".

There are awards, patents, accomplishments, etc.

There are positive correlations between IQ and positive outcomes in general. Basically, take a metric of success and group people into it and you'll find people with higher IQs in the groups with better outcomes.

Even if you then slice those groups by other factors.

I already covered that contingency. All the other criteria you've mentioned are qualitative. Which returns us to income levels, which again, IQ doesn't predict very well. And the claim that you'll find people with "higher IQ" (not clinically disabled), to be more successful is specious because you're including the portion of the tail that is dysfunctional.

First, in terms of salary, people with below 80 IQs aren't included because they generally don't have jobs.

Second, why would we even have to cut off the tail portion?

Next, you didn't cover that contingency. You keep saying it's all income levels, but it's not. IQ and positive outcomes are positively correlated. Pick a thing, pick a measure of success, you'll find that people with higher IQs will tend towards the successful group.

And this is also a "all doctors are tall, not all tall people are doctors" kind of statistic. Higher IQ people will wind up in the more successful groups more often, but being in the more successful group doesn't mean you have a high IQ.