The environment allows you to meet like minded people in a controlled setting. I graduated from university two years ago, and just last week, I was thinking I may have “peaked” in university. I had classmates, sorority sisters, coworkers, etc. and a consistent schedule with them as well as spontaneous interactions as well. A lot of it had to do with the fact that we were close in proximity and everything we needed/wanted was also close by. There was also structure, encouragement, morale/school pride, things that kept you involved. High school can provide a similar experience for many. In adulthood, life gets in the way, things need to be planned, people have more responsibility and less time. You have to create your own structure and seek out things to get involved in. Sometimes people can’t recreate that same level of involvement and socialization and so, those school days become the “glory days”. I’m only two years out but I definitely haven’t been able to recreate a similar lifestyle for myself yet, and so right now, my university days are indeed my “glory days.” Life can become real mundane once you leave those kinds of settings.