A cynic might say they spent most of that for King, which continues to be profitable. The rest of Activision Blizzard just came along for the ride
It does print money, but it is also extraordinarily expensive to keep the money-printer fed. Current estimates place the production + marketing costs of a Call of Duty north of a billion dollars.
At that kind of spend, it only really takes 1 or 2 botched releases to make the financial equation look a whole lot less rosy...
1. a long dragged out distraction over decades trying to make it work
2. a painful but quick 40B write down and the ability to refocus the company on better projects tomorrow
.. then they are, quite rightly imo, going to pick #2. In fact I would assume this going to be the next announcment.