Oh, by all means, please enlighten me.
Ahahaha, my turn to say, "yeah, no". You don't know shit.
Yes, thank you smartass, I know what revenue is. And yes, I did actually account for the costs of running WoW. That was my point in saying it does not cost $15 million a month to maintain. In fact, allow me to give you the estimate that my research has turned up, since Blizzard has never officially (and never will) released maintenance costs: $120,000-$150,000 per day, or less than $5 million a month. That means they would still be making a profit on as low as 666k subs ($10 million / month). ALL OF THIS is without factoring in the cash shop, mind you.
Please, prove to me that the game has less than 1 million active subs. You can't, that's a number you pulled out of your ass for the sole purpose of being a contrarian. It is undoubtable that WoW still has a minimum of 1 million subs across all 4 continents and both versions of the game.
The assumption that every sub is paid for with $15 is for the sake of mathematical simplicity. The MAXIMUM variance in that is $5 in either direction; some countries pay the equivalent of $13-$14 USD per month, others pay the equivalent of $17-18, obviously the 6-month sub gives a $3/month discount, and the Blizzard sees $5 more per WoW token than they do for a direct sub. All of that makes averaging it to the baseline $15 completely reasonable.