Fully agree. Culture is everything.
I will say, however, that having left an Independent PK-8 school, I worry more about the parents than the kids. I watched some very uncomfortable behaviors around the Secondary School admissions process that were clearly parent-driven. There was a lot more mania around “Where are you gonna go?” amongst the parents than the kids.
I say all this to say, sometimes its the parents that the kids need insulating from and that the right boarding school can help with that. As I tried to say, I don’t (and didn’t) see much peer-to-peer competition. It is and was mostly internal. But I only have perspective from one place, where, for the most part, the kids love and root for each other.