I’ve been working with students applying to colleges for several years now and one of the biggest mistakes parents make is forcing kids to miss out on normal high school experiences in the quest for admissions to an elite school. The result is often an uninteresting kid who has very little to write about in their essays or for teachers to say in their LORs that make the student stand out. So OP, I’m sorry your son was rejected and even more sad that he missed out on high school trying to “do all the right things” to get into UChicago. Please let that be a lesson learned and step way back and let your son forge his own path. Don’t micromanage his college experience like you did his high school experience. Most kids will thrive where they end up if allowed to find their own way. He will be fine. Good luck to him with his RD applications.