Why is it a sad state of affairs to lose interest in a hobby? It's the sort of thing that happens all the time to most people. It just usually means that you are ready to move on to something else for your entertainment needs. I've gone through a comic book phase, baseball card phase and plastic model building phase. These were all hobbies that I eventually lost interest in and moved on.
You're obviously right, but I actually find myself with a "lack of something to do" in the workday evenings, especially with bad weather. Motorbike and other more "real" hobbies just aren't always available, and sitting in front of the TV isn't a decent alternative either.
So part of me still wants the ability to lose itself in a game (worked wonderful with Skyrim). There just isn't a game currently that will let me do it (perhabs F3...)