They won't give away hundreds of millions, or more, without having a way to recover that money. MS started to integrate Bing searches in Windows 8.x that is nothing more than tracking end users in the OS. While one could disable this integration in Windows 8.x, in Windows 10 it's not an option. As the matter of fact, Cortana needs an MS account just to work, not to mention that detecting location needs to be enabled as well. Who needs tracking script when MS can have people jump on the "free" Windows 10? Can you imagine the advertisement income MS will have from Windows 10?