Jana and I started playing World of Warcraft in early 2010. It pretty much immediately became and stayed our main hobby, and a major source of our enjoyment.
Most people - including us before we started playing - have the idea of WoW players as insufferable nerds, addicted to a game, with poor hygiene and no social contact. In addition to that, there's the concern about paying $15 per month for a game.
So let me tell you why I think World of Warcraft is the perfect hobby.
First off, the price. $15 per month is probably the biggest bang for the buck you're ever going to get for entertainment. Compare it to the cost of a single dinner with friends, or tickets to a movie. Then consider that you're likely to play WoW a lot more than the two hours it takes you to watch a movie.
WoW occupies as much or as little of your time as you want it to. You can play it 3 hours a week, or 30. There's always something to do - raiding and battlegrounds if you feel like high-stress action. Dungeons for a medium-stress activity. Questing for a low-stress way to spend time.
The main character you play is a lasting investment. Once you find the class that most fits you, the skill you develop with it allows you to enjoy the pleasure of mastering something you love, and it pays out for years. One of the main payouts, for me, is the smug satisfaction from when I see how much better I'm at it than people who haven't played as long as I have.
You can play alone, play socially, or play to test yourself against other people. You can play the game every day for years, and still not explore everything.
Some self-control is necessary to enjoy it. The game is so huge, you can't eat it all in one sitting. It's better if you don't try. For it to be a good part of your life, you need to treat it like a long-term hobby; something you can separate from, and come back to. Something that's going to be part of you for a while to come.
I've played other games; I've even quit World of Warcraft for a while. But I keep coming back to WoW because it's an enjoyable game that's not ephemeral; a game where your investment is worthwhile.