Whoa. My 10 year highschool reunion was a looong time ago. I'm getting old.
I was surprised, or maybe not too surprised, that many people had not changed at all. The only difference was that they could buy booze legally. They were the same mediocre sods they were in HS. That's the explanation for them not changing.

Some people really changed and blossomed which was good to see. Those were mostly the "nerds" who managed to shake that stigma.