I help support an app with just a few thousand users (US and Canada). It's about 9 years old but still actively updated. Coincidentally, it's user base is decidedly poorer people. In the years I've been involved there have only been a handful of people running macs and about the same number running Linux. Easily 99 percent run Windows. XP was most common until last year when Windows 7 finally took over. The first Win 10 users are just starting to show up.

My (admittedly limited) experience is just the opposite of yours.