You were just shown statistics that disprove your idea that almost nobody codes using Windows... over half of the developers who answered StackOverflow's survey are using Windows. Pointing at more anecdotes around you does not change this fact.
It's hard not to look around with your own eyes and notice that you never see anyone using Windows - like I say, even the Microsoft ones!
Do you meet a lot of developers using Windows? What kind of circles is that in?
The games industry is primarily Windows based.
I would generally say that native Windows development is in decline, but it's a long slow decline and it's starting from an incredibly high base.
"a rounding-error of zero" is so wildly incorrect that it is very clear you are in a bubble of sorts.