Cars Won't Get You Laid

Eternal middle schoolers is true. They didn't make it in the adult hierarchy, but high school was the best four years of their lives. So they regress to middle/high school when they had it good, group up together, and continue middle school into their golden years.
The root problem is that we allow kids to form a separate hierarchies in the first place. Traditional societies put kids at the low end of the adult hierarchy, only higher-status than criminals. They didn't get to form their own hierarchy with different rules. This way, everyone wants to become an adult, and everyone is working toward fulfilling the adult standard from the get-go.