Sure World of Warcraft could be receiving billions or hundreds of millions in revenue but they could also receive millions of expenses too. It is unlikely though that Blizzard's World of Warcraft expenses exceeds their revenue. But at the same time we don't know exactly what expenses they incur. I am not even sure if they make a billion dollars in revenue considering that Asian countries don't pay a flat out monthly fee but rather a usage fee but that's a discussion for another topic.
So just because you see revenues posted on the internet about a company, don't take it as the end of all or even a major success, because a lot other things such as expenses, cash flows, and future investments are also needed to take into account to determine how well a business is performing. But if you're not about going into great detail on a company's financial performance, at the very least look at a company's yearly or quarterly profits to determine it's year to date success.