It's estimated an average person can only gain 5 Iq points via education/environment.

There are countries where the prevalent concept is that everyone should go to university and get a degree and intelligence doesn't matter. Parents spend a fortune on private tutors and private schools to get their offspring into university, and even then you end up with young adults who are clearly not able to grasp slightly complex concepts or even write a small essay. While other kids study on their own and succeed using minimal means.

However, because society thinks that intelligence doesn't matter, we end up with all of them treated the same, getting the same degree through a system of corruption and favoritism, and the result is the global crisis we witness these days.

On the other hand, nobody says that everyone can be a football player because genetics don't matter, and the crowds worship athletes who are often unable to utter a coherent sentence. Sometimes they are elected as MPs and the result is embarrassing.

EDIT: I should add that I'm talking about relatively racially homogenous countries, and what I described is not US-specific.