I don't get how "It sold half of the PS4" is seen as some type of success. Instead of comparing the XB1 to PS4 we should compare the XB1 to it's predecessor... The XBOX 360
XBOX 360 - 87 Million units sold
XBOX One - 55 Million units sold
That's a 30+ million drop in customers and user base. A cataclysmic failure. Framing it as "half" the PS4 doesn't begin to address the actual reality of the situation. For example... I'm an EU gamer. I game and am friends with people from Germany, France, Hungary, Sweden, etc etc Do you know what happened to the XBOX brand according to my European gamers, outside of the UK?
According to them, while PS was the dominant brand. Since the launch of XB1 the brand doesn't really exist outside of a few hardcore enthusiasts. While PS has become the de facto console of choice.
That's market share XB can't, or at least to date, hasn't got back. And while we put huge importance on acquisitions, on the ground nothing beats "Where my friends play." At least here in Europe.