How much I could sleep!

Having access to so many resources like huge art studios, good computers with software I didn't have to pay for, niche/out of print books in out of the way corners of the library...

My "job" being, in many classes, to read/learn interesting things and then go talk about them with other people once or twice a week. I wish I could get paid to do that now without going into academia.

All the activities you would walk into on campus. I might be walking around in the evening and see a music festival with free food, or there would be a Holi or Diwali party, or a sex trivia night, or a silent disco, or a drive-in movie, or a Pokemon Go get together... And it was all FREE! You can still sometimes walk into a fun group activity in the adult world out of college but the probability is less likely, you usually have to plan to do it ahead of time, and it isn't free.