That assumes an equal amount of work. For those with high IQs who do not apply themselves, the results are not so stellar, and those with low IQ (often willing to take risks, perhaps because they do not understand the downside), hard work pays off, more often than not.
I must also note that those of us who have performed well on the tests are more likely to defend them.
IQ provides potential, not results.
A person of below-average IQ, no matter how hard he works, will never be a stellar performer in occupations requiring high IQ.
OTOH, a great many high-IQ people spend a lot of their time and energy bitching about the fact that people they work with who aren’t as smart are doing better than they are. Don’t believe me? Attend a Mensa meeting.
Think of it as height. A very occasional person under 6’ might succeed in the NBA, but in general those who succeed are above 6-6. The taller they are, the more likely to succeed. That’s because you can teach the skills, but you can’t teach someone to be 7-2.
Again, a 7-2 person unwilling to work hard would not succeed.
No, it doesn't assume anything, and neither should you. The data is what it is, and the math indicates a strong correlation.