Your brain isn't developed (it keeps developing till at least 30) to the point that you are capable of acquiring that expansive world view during those first 12 years. There is a reason we don't trust teenage drivers, and part of college is that transition from being a teenager to being an adult. In high school you are still only seeing people from your neighborhood but people go far away for college where they meet people who are totally not like them.

(Yes, people mature at different rates and some can acquire some of that world view in High School.)