The point is: statistically, having above average IQ can give you some advantage. Maybe 5%, maybe 25%. The same advantage can come from many sources, like: be born on the "right" country, have a certain weight, height, skin color, religious belief, economic background, etc.

Think about the USA. The year and city where you're born/raised can outweigh your IQ when trying to predict income, life expectancy, etc.