10 million copies at roughly $29.99 a copy [not counting extra cd keys sold for mishaps and such or side-sales, such as books, movies, t-shirts, etc.]
That would be roughly: $299, 900, 000
Why don't you start with packaging? That's a pretty nice box the games and battlechests come in. My guess would be in the $5-10 per range (no, I'm not joking).
So, we're down to $25 a copy.
The retailer gets about $15 of that, so you're down to $10 a copy. And don't forget the distributer and publisher (even if that's Blizzard, the department still gets paid), so you're probably looking at closer to $5 a copy if you're doing really well.
10 million at $5 a copy gives you $50 million. Now take out development costs, upkeep, server maintainance and everything else and see what you end up with.
As a Socratic inquiry, how many companies are still actively supporting (as in adding new content and patches) 10 year old games?