Just one Billion Windows users?

[German]Microsoft's CEO, Satya Nadella, has been interviewed by Bloomberg. During this talk, he mentioned also the number of Windows users – which caused a surprise.

We have been on 1.5 billion Windows systems

Back in my head I've stored, that the shall have between 1.5 and 2 billion Windows user. That's because in 2014 Tony Prophet revealed 1.5 billion Windows systems on Windows Partner Conference (see the transcript here). 

And Windows is becoming the gold standard for mobile device management and security and it's a platform built on the scale of 1.5 billion users around the world.

I've found this number also at neowin.net, whilst Paul Thurrott named within this article different figures: Windows + Office have had 2014 more than a 1 billion users, and Microsoft mentioned 1.3 billion Windows users. Business Insider werites about 1.25 billion Windows systems.

Now we are at 1 billion Windows users?

Let's go back to the Bloomberg Interview – where Nadella answered many questions (unfortunately I didn't found a transcript). At MS Power User and at bitfeed.co Nadella is cited, that we have worldwide 1 billion Windows users. Well, it was just an interview, but most observers were puzzled and asked themselves how the loss of half a billion Windows users can be explained. 

There can be many reasons for these discrepancies. One would be that at some point in 2014 they simply miscounted themselves. Or people move away from Windows to Apple or Android. And there is another insight: in the past, when we all were young, there was a Windows PC in the family, and there were several users sharing this device. Today, a user may have a Windows notebook, an XBox and also a Windows Tablet as well as a Windows Smarthone. The number of devices is greater than the number of users.