Rather than an 'unhealthy obsession', geocaching has certainly become a 'healthy option' for us as one of us used to be an athlete, but due to a leg injury and several operations later, they cannot now use running as part of a healthy lifestyle, but walking is still fine. We both still work (and put a lot of effort into that and our family and home), but we do enjoy planning whole days of caching, whether as long or short walks, or varied driving trips, home or abroad, and we always look forward to new areas and new challenges.
It is keeping us active (and indeed we are out in the open far more than we used to be), our knowledge (even of our own local area) is ever growing, and we often truthfully say to CO's "thank you for bringing us here - we would never have known about this if it hadn't been for geocaching!"
So an obsession it may be (?), but for us it's a healthy one, and we are happy with how it has fitted into our lives so well! So we very rarely feel guilty or irresponsible!