I have been a Linux user for several years, and my laptop has run various flavors of Linux during that time, with nary a whiff of Windows. In my case, Linux suits my purpose and does what I need to do - so I am not hater.
Having said that, Canonical's stated goal of 200 million Ubuntu users in 4 years has fallen laughably short at the end of 2015 - less than 25% of that number, in fact. Disappointing, to put it mildly.
I suppose if you lump all the Ubuntu-based distros together, you would get a pretty good user base number, but that's not what Canonical had in mind, I am pretty sure; they meant Ubuntu users.
Of course, various Linux incarnations are powering lots of things from Supercomputers to Android devices - just not Ubuntu Desktop systems.