Personally, just making contact with my bass and playing it (not much more to do) gives me great joy. Whether I'm playing someonelse's work or messing around with it and creating something original, it is never the same and I never get bored.
Not everybody wants to be a rock star, but there are still many good reasons besides looking at playing as a career option.
-It helps keep my mind off petty problems I'm facing. If it's a big problem I'm probably writing about it. :-D
-Reading notes and trying to get the right hand positions has made me more attentive, not only when playing but in general.
-In the long run it's probably going to be cheaper than spending hours in front of the tele or playing your Nintendo.
-It's one thing to listen to your heroes play great music, but to play their music gives you a whole different feeling. A bit euphoric sometimes.
-Helps you meet new people you might never have met if you didn't share a common interest in bass or playing music. A jam is always a nice way to get together and enjoy your time.
-THE OPPOSITE SEX DIGS IT!!! :-D