Center stated it perfectly. It is JMHO and based on my informal observations but I truly believe no matter where you are applying, if you can be a unicorn or contribute to some type of diversity for the school (ethnic, racial, wealth, geographic, talent, interest, ability), you will have an advantage. Boarding school kids tend to be rich and that’s great for the ability to be full pay. But really, that’s about it. I know someone who actually took their kid out of an elite private school and transferred him to a public school because the parents realized colleges were not looking for the boarding school type kid. (don’t shoot the messenger) So when applying from top (often private/boarding) high schools, you have given yourself a level of competition (your own school) as an additional hoop to try to get through. Gone are the days when schools are looking for students from the most elite places. Now schools are looking to diversify their student body.