That's ... not how it works though. You're only accounting for very surface-level expenditures.
If that were true, try to apply this to PlayStation, because we know the full details of their numbers.
If the game development costs are only $1.15 billion per year ... let's double it for no reason ... let's make it $2.5 billion per year. PlayStation's revenue was $25 billion in the last fiscal year. So that means their operating profit should be more than $15 billion, at least, even if account for the 70% returned revenue for third-party software sales, right?
Their operating profit was only $3 billion. So $22 billion of operating expenses in 1 year. And they had fewer studios and developers than Xbox.
Why do you think they have an operating expenditure of $22 billion per year if the game development cost, as per you, is only $1.15 billion per year?