Again, it's not always "just" about missing friends. It's sometimes about losing one's sense of security.
On forums like this, the majority of posters are wired in such a way that longterm travel is enjoyable. But for many many many people, it's not. For them it's stressful, it's lonely, it's not enjoyable.
There are so many posts about how young people are selfish and don't give a flying fig about other people, but some of these posts are disturbing in that the older generation doesn't seem to give a flying fig about their own spouse. Why should a 20 year old care about a stranger when granddad says "I told my wife i'm going with or without her so she can shut up, get in and hold on. I'm not sitting around visiting grandkids when I can be out meeting new people".