Those first few days after mandatory education was over were a really weird and surreal moment for me @ 18 years old.
Schooling is this period of your life where the routine of going to school, homework, school holidays etc are pretty much the only thing you know, but then suddenly it slams into the buffers and it becomes irrevocably over.
In the UK system you usually spend 7 years with the same cohort of kids up to 18. It felt to me like a lot of social "baggage" gradually accrued over time - you built up this persona/reputation/expectation that defined what sort of person you were, how you acted, what sort of friends you kept, what you liked to do etc. It seemed to me that you unconsciously lived-up to this view that others had about you - people thought you were a smart kid/popular kid/sporty kid/nerdy kid, and so you acted like one.
Once school was over though those expectations from the others about who you were and how you acted just evaporated and you were free. Kids would be well-served to be reminded about this! Everything changes after school.
1. I stopped being afraid of losing a fight. I learned that if you got into a fight and and got in a few good hits, even if you lost, people would be less likely to give you crap in the future.
I might go home with a busted lip but you're going to pick up a bloody nose for your trouble.
2. I got bigger. I grew to be 6'1" by my senior year. Bullies go for easier targets and someone who was their size or bigger wasn't usually an easy target.
I don't advocate violence as a first resort to solve anyone's problems but it's important to be able to defend yourself.
It does go on forever.
The only difference is that the "opt out" option is unlocked after high school, but opting out has consequences. Even if we don't want to admit it, there's a lot of truth to the phrase "It's not what you know but who you know".
I hung out with plenty of nerds in high school, and most of them took solace in the belief that they'd eventually be laughing all the way to the bank while the jocks were flipping burgers. It's one of those things you keep repeating to make yourself feel better even when you suspect it's not true (kind of like people who say "I could've been popular if I wanted to").
Turns out they were wrong, and I'm guessing it's because popular people are able to use their superior social/networking skills to easily find job opportunities (and promotions), while nerds struggle to find the courage to answer the phone when the interviewer calls.
The other dynamic, is turning 21, where you can hang out at establishments that serve alcohol. Which helped with the social anxiety -- so from my mid 20's on, I didn't have any of the issues that I had back in high school.
"If this doesn't matter, why am I in so much pain?"
The trick is that it both does matter, but also isn't permanent. So little of what happens in high school is irreversible, and certainly almost none of the things that feel permanent are, but it's hard to explain that without minimizing legitimate feelings.