I think what is often missed in mainstream discussions on "giftedness" is those gifted but with disabilities.

https://en.wikipedia.org/wiki/Twice_exceptional

These are students that are gifted, but due to their disabilities underperform. It isn't uncommon for them to not be identified as gifted, and thus never be put in gifted classes despite being very intelligent.

Imagine having someone 140+ IQ that is stuck in a standard classroom all 12-years of their pre-college education because they weren't ever identified. They typically are the students that enroll in special services and get exam accommodations in colleges.

At least colleges recognize these sort of students. For example Princeton has such services: https://ods.princeton.edu