Isn't the biggest part of the costs the manpower ? like the coder, the graphicer... the 3d artist etc.... ????
Let's say that the average salary for one of those talented people is $80000 per year. Let's say you need 25 of them for one year (that's a reasonable budget for a small console game).
That's already $2M just by itself, not including all the other expenses (business costs, office space, utilities, hardware, software, legals, tax, marketing, travel, etc, etc).
(Talented) Manpower is expensive.
And that figure is also assuming that the developer is making zero profits, and is giving the publisher's money straight to the staff without keeping any for themselves! Keep in mind that many developers/studios do not get any money when you buy their games -- the publisher pays the developer/studio up-front to create the game, and then the publisher keeps all the money that's made from selling the game. In these kinds of arrangements, then the developer/studio of course has to add 10%, 20%, 50%, 200%, etc, onto their initial bill so that they actually make a profit from their work.
These days, I'd guess that $2M is a very cheap console game, $10M is your average console game, $50M-150M is your big AAA games.