For a big company, there works 50-100 people |
Actually for the larger AAA games and studios there is quite a bit more people working on it then that. It is not that uncommon for there to be around 1,000 people (Red Dead Redemption had around 800) working on the game throughout it's creation. These range from programmers, artists, sound artists, Q&A, management, executives, etc.
The lowest paid of all those listed is probably the Q&A department but they still make quite decent salaries ($18,000 - $50,000 though usually in the middle). Whereas senior programmers, management, artist and executives tend to make quite a bit more.
That is just the salary side of things (For a single year also, which Ceset mentioned a lot take more then a year to complete).
Then there is publisher and or marketing costs which can cost millions for larger games. Then as Ceset mentioned they also have to pay for other things like voice actors, motion capture time if they don't have one in studio, equipment fees (Servers for example), middle ware royalties and a whole range of other things.
To put it plainly big titles for games are basically the same as motion pictures now days and their expenses are quite similar.