As I only did one semester of uni I can't really discuss moving apart from those people.
However, have I lost touch/become less close with my school friends? The majority, yes. I went to an all girls school and *****iness was inherent. I still encounter some friends from then now, and we don't get on. Some people have also moved away or are doing different things. However, two of my best friends are friends I've had since we started secondary, aged 11. We talk all the time and hang out, even though there was a couple of years where we barely spoke. There's also one friend who I disconnected from for years because of the aforementioned b*tches, but we've become good friends again recently and we hang out a lot because she lives nearby.
As for college (sixth form), I haven't seen any of those people since I left. Like, seriously. My college was huge compared to my school, with 4000 students compared to only 600 (just 120 girls in my year). Even from first to second year, I didn't hang out with the same people. In first year I was so ingrained with one group and then I realised I wasn't enjoying the constant drama surrounding them (plus I had a nervous breakdown in the summer before so I wasn't quite there) so in second year I was sort of a nomad, going from group to group with no close friendships really formed other than maybe one guy who I still talk to occasionally. But then obviously I went to uni and dropped out and now work full time which has alienated a lot of people. I mean, because of that, I've made friends with people 10 or more years older and some of my older friends my own age don't know how to even talk to them. Also, my life is totally different from people still studying. They look down on me because I'm a drop out but I've become way smarter and more grounded as a person than them, at an earlier stage in life, so a lot of the time I find myself kind of condescending them by accident.
I do think it's a part of growing up but also, life takes you in different directions. And sometimes I think your friendship only works in context and you can't take it out of that context, like your best friend in school could be someone you have zero in common with outside of school. Because, at the end of the day, school is not the real world and you realise that as you get older.