You missed the biggest reason: - Networking with people all assumed to be at or above a bar dictated by the college acceptance committee. This is point is hug

You missed the biggest reason: - Networking with people all assumed to be at or above a bar dictated by the college acceptance committee. This is point is huge, given how spread out the US is many students may have never had that kind of opportunity. The things you learn from your peers, all naturally aligned in the community are orders of magnitude more than what you learn in class and can't easily be replaced by online resources.