Staying in contact with friends is a lot of effort. As people start jobs and have kids you have less and less time. It gets harder to schedule meeting meeting people. In high school and university spending time with someone was as simple as texting "Hey wanna come over?". Now I have to schedule things days or weeks in advance and half the things get cancelled because the kids got sick or something.
Binge watching Netflix on the other hand is easy. I can do it whenever I want.
The answer is pretty clear. University is the only time for most people where they live in a walkable area close by to their friends. Then they move out to the suburbs and become socially isolated for the rest of their lives while their initial friendships slowly decline. And now with working from home becoming common, we will probably see huge numbers of people who simply get no social interaction at all in their lives.
Sure and that's actually where I developed my love of walkability and bikability. But I live in the "bike-suburbs" (everything in easy biking distance or walking distance) and even then as my friends and I got older, it became harder to socialize. We still stay in touch frequently, but planning flesh meetups became a lot harder. For us it was mostly prioritization. After a while we all started prioritizing our family lives over our friendships. It started when most of us entered serious relationships. After that point, it became harder and harder to meet up. I sometimes wonder whether the tradeoff (choosing family over friends) is worth it but I still find that it is.
Binge watching Netflix on the other hand is easy. I can do it whenever I want.