To be fair, that only leaves 10 hours a day for the person to do anything else, and presumably 6 - 9 of that is sleeping. Optimistically, that leaves 4 hours a day to do things like eating, grooming, chores, job hunting, etc. So the extreme amount of gaming may start as a "symptom" as you say, but I just can't see how that person could really ever effect any change in their life when they spend literally almost all of their time gaming.