My kid's school is based around the theory of Multiple Intelligences, which is very much in line with your thoughts - there are different kinds of being smart, and different ways of being smart, and one of the benefits of her school emphasizing and teaching the different intelligences is that there are places for every kid to shine, and places for every kid to struggle, and no subject is more "real" or more important than any other. Maybe your friend's kid needs some exposure to a subject or subjects that are hard for them - a team sport, or a creative endeavor, or a class in social-emotional learning - to make them aware of the fact that there are things in the world they are going to have a hard time with, and that's okay. (Also, from the perspective of a former "gifted kid" who never had to put much effort into doing well in school, and who therefore never learned how to practice something to improve at it, and quickly moved into a space where I didn't do things I wasn't immediately good at because everyone expected me to be good at everything all the time and didn't give me space to be bad at anything... the earlier this kid finds something hard that they have to actually work at to improve, the more helpful it will be for the rest of their life.)