Does World of Warcraft ruin lives

No. People have free will and can choose to play or not, just like a person with an alcoholic addiction can choose no to drink anymore. It may be hard, but it certainly doable. The problem with any game (computer or not) is in becoming so immersed in the game that you either put off responsibilities in real life (IRL) or you cease to do anything else. The competition to be number one is even stronger in people when the game is very anonymous like Warcraft, or Runescape or Guild Wars or ..... (and so on.)

Like online romances, people often choose to continue their self-destructive behavior rather than do anything about it.