physically this game can be horrifying. People spend months grinding honor to hit Grand Marshal or High Warlord (highest PVP rank). People quit their jobs/take time off to farm honor. and lose tremendous amounts of sleep over it.
There was one guy who lost everything playing C&C on-line...he even broke his leg running up the steps after he quit his job. His girlfriend broke up with him twice and he became anti-social.
I'm sure it's ten-times as bad for the true addicts of WoW.