You're confusing number of people with percentages. There's still a large share of people who'll pay to use software on windows or android provided your software is good enough. This wrong impression comes from the fact that many users are from 3rd world countries who can't afford anything else. Steam made their entire business selling stuff on windows. And not just proprietary software. Many blender and godot addons are paid and nobody complains. Apart from developing software, where linux and osx are far ahead, in terms of industry software such a autodesk, solidworks, rhino, flstudio, etc, windows is THE platform you want to target of you are planning on monetization. And I'm saying this as a exclusive linux user of 3 years. You know who won't pay money? Linux users. Not out of lack of it, but mostly because of principle of FOSS software. And yes, I'd rather use a inferior FOSS alternative than a slightly better proprietary one

Everyone I see who doesn't use Linux uses a Mac.