I have a friend like this, and yes, at times it can seem like he's "addicted" to WoW (although I'm not sure I know what the word means anymore after glancing over this thread).
These two things helped him downgrade from addiction to hobby:
1) Teach him how to play another strategy game with just as many options. For example: Magic: The Gathering, Starcraft, Command & Conquer, etc. Great wastes of time and money, and hopefully he'll switch his budget over to the new game or pick his WoW months. It's also helpful to learn this new game with him, so it'll be more important to him.
2) Remind him that no matter how good he gets at WoW, he probably won't win money. Then point him to a gaming community like Halo 2, Street Fighter 3: 3rd Strike, or Super Smash Bros. Melee, which are (comparably) easier to learn and tougher to master (opinion).
Note: Where exactly is the enjoyment factor in WoW? If leveling up is not a thrill for me, is there even a game to be had? I personally prefer zero-sum competitive games because they are just as stimulating (as far as combat strategy) and there's so much less information!