For example, in New York City, it seems the main activity for young people is to go out to bars and restaurants.
You pack your bags and head somewhere tropical. You pick up a water sport like surfing or kiteboarding. You start waking up at 6am with the sunrise and realize it's amazing. Back in NYC, your awake hours were more like 10am to 2am. You start cooking at home.
Now, you look back at your friends and view them as wasting their life in bars and restaurants. You start identifying with the older crowd who comes to the office at 6am or 8am instead of 11am. You also start wondering why your friends don't ever do anything outdoors.
When you move, you end up with new habits. Your brain has a need to feel correct, so it views any changes as improvements; therefore, the ways of before (and of your friends) are now considered wrong, otherwise your mind experiences dissonance. You'll find a way to justify things to stop the dissonance.
When I got back I felt that I had thoroughly changed, yet my friends and family considered me to be the same person I was when I left. How could they do anything else? They couldn't possibly know what I had been through. To them I had just been away for a (short) while. To me they started to feel narrow-minded and set in their ways. The things I now found interesting weren't interesting to them, they couldn't understand them. The things they found interesting had lost its appeal to me.
I went on a trip to Pakistan and on return, it's like I can strike a conversation with a Pakistani/Indian/Nepali anytime anywhere but with a Chinese or Caucasian (I'm Asian Australian)? It's harder to build rapport and feel connected in conversation. It's still possible, but I notice it takes a little more time. I think it'll even out over time, though, since I wasn't in Pakistan too long.
The author of the parent comment may have a different perspective.