ROI lags. If they laid off 90% of the Xbox division and left only enough to keep the lights on (they don't run their own factories I guess), then they'd still get nearly the same amount of income the next year with far lower costs. Of course revenue would start to sharply decline as the number of games produced was much lower, as the tech became obsolete. But it's not like revenue would evaporate instantly.
So they could do that and invest the income they still get into bonds, and then that would be where the returns come from.
They don't want to do that obviously, hence why Xbox needs reform.