As we always say here, boarding school is about a stellar high school education, not college outcomes; colleges admit students, not high schools. The types of students who are cherry-picked by boarding schools are those likely do very well with college acceptances from any high school they attend, public or private.
I think this thread is valuable in highlighting to prospective families how important it is to do thorough research on the schools they are considering before applying and encouraging using this forum as one of those research tools. There is a lot of institutional capital here and many experienced parents who are willing to share the highs and lows.
Our son is ten years out of BS and quite grateful for the experience, especially the strong preparation for college work, the peer collaboration (not cutthroat), the time management and self-advocacy skills, and the early independence gained. For him, it was a very smooth transition to college, even to a service academy. He hopes to be able to gift his own children with the experience someday as he definitely considers it worth it.