I believe that school selection is very important for profoundly gifted children.
My hypothesis is that children can thrive in a school where their IQ is within two standard deviations of the mean. If that's the case, they will have some academic peers in the school that they can relate to. If they are 3+ standard deviations away, there is likely nobody near them intellectually, and that can make for loneliness.
My children attended a public school system where the average SAT score is over 1300. Even though they were near the top of the class, they still had a number of very smart friends their entire time in school. They were well liked and my son was even elected as middle school president (no president in high school).
My son connected with the mainstream students through sports, music and extracurricular interests. He did attend Yr 5 & 6 selective classes with students from a much wider geographical area. Many years later, he described how he had excitedly looked forward to these classmates with whom he had expected to be able to share his intellectual ideas, but was disappointed to find that the selective class students weren’t qualitatively much different from his previous classmates, which influenced his decision to turn down an offer at a selective high school, which in hindsight, was the best decision, giving 2400 extra hours (over six years of high school) to pursue his own interests. He is now at a prestigious university and has connected with the best and brightest from many of the top schools across our country, by mutually engaging in a wide range of academic, sports, music and arts activities.
ETA: My daughters both started school early and were 6-18 months younger than their classmates, so whilst they both eventually ended up academically at the top of their year, I think they always felt comfortable and at the right grade level. Early entry wasn’t an option for my son as he was deemed not socially ready, whereas the girls, my eldest in particular, had/have excellent social skills.
