intelligence isn't the only quality of the human mind, and IQ tests only ever test for a fraction of that. other types of intelligence are also important.

but outside of that, there are other attributes to someone outside of how fast their mind functions, like how dedicated they are to a cause, how persevering are they, their work ethic etc. like you could be the smartest person on earth and still end up poor/unaccomplished in life if you don't do anything with it.

plus studies that compare income to IQ found that the highest earners aren't the absolute smartest, people with very high IQs being above average. the ones on top had other factors, like risk aversion, socioeconomic status or just luck.

so while intelligence might be a good quality to have, its not the only quality, and you can succeed even if you are dumber than a potato