Uses =/= being good. Arguably especially for Microsoft, they're the anti-thesis of each other.
Gamers use Windows because (until recently, and even still only in specific contexts) you need Windows to game properly. Thankfully between things like the Proton framework and broader support for Mac and Linux gaming, that's starting to change.
People in business and government use Windows because Apple has never prioritized the Enterprise environment in MacOS, and it shows. And to be honest thank fuck, otherwise MacOS might be as bad as Windows is now.
A whole lot of regular people use Windows at home, because it's just the default and you can get PC's for dirt cheap (pre-tariffs anyway) that come preinstalled with it. However that market is eroding as people go full time on smartphones for general computing and computers become less relevant overall.
I'm not saying Windows is going away, the inertia is incredible there and I suspect they'll continue trotting along, being mediocre and pissing off everyone continuously because that's really what they've always done. But let us not pretend financial success in the market is in any way an indicator of a good product. Like evolution, markets do not select for "the best" they select for "the okayest" and Windows is very much the okayest OS.