There have been many threads on this subject over the years. It never gets old. I will try to find more links when I get more time, but here’s one and another and yet another. In the meantime, perhaps others can add to the list.
Best response, though, is to smile and nod. You do not need to justify or explain your decision to anyone. To anyone who was sincerely curious, I simply explained that our son found what he was looking for in the school he chose and we allowed him to go. Though we missed a lot, he missed nothing. After all, it’s all about him and not about us. I never offered anything that could potentially make the local options seem inferior. Should a conversation appear to be going south, you can always excuse yourself to freshen your drink.
Our son’s choice of a service academy for college brought out waaaaaay more idiotic questions than BS ever did. I got quite good at saying, “I know! What the heck was he thinking? He’ll probably just get himself killed and then all that boarding school money will have gone to waste. Excuse me, I really must find another martini.”