> This is still $150M of pure gravy every single year

You're neglecting to consider that any time they acquire a studio or have a flop or two -- poof goes that $150M and probably more. It's not a risk-free venture. Entertainment is all about hits, and misses hurt.

Would you put up $5K to win $150 on a hypothetical roulette wheel that hits 90% of the time? The math's not perfect obviously but Xbox is a somewhat similar situation. Microsoft is putting up nearly $5B a year to make $150M. They'd be better off stuffing the $5B into bonds or something. There is a point where the returns aren't high enough to justify the expenses when risk is taken into consideration.