> Where are there no companies like the Omni Goup, Cultured Code, and Panic turning out great applications for Windows? In theory, the market is an order of magnitude bigger yet the reality seems to be that there are fewer Windows users willing to pay for great software. Is it because Windows users are not on that platform by choice?

There are such companies! For video games. Video games and B2B/business-productivity software is where the money is on Windows. Your buyers are PC gamers or businesses.

There are also lots of unsophisticated low-needs users who are on Windows at home because it's what was cheap at the big box store, and/or they learned in the earlier PC days to shop based on spec numbers back when those mattered much for basic home users, and the Apple section of the store doesn't look very interesting if you shop that way.

AFAI can tell (from watching relatives fitting this profile, which is... all of my relatives, plus many relatives of friends) the only way to make money off them, since the death of actual boxed software in stores (which they did used to sometimes buy!), is to be Microsoft and use Win10 to spam them until they buy (maybe not even realizing what's happening or, once they've paid, what they bought or what it's for or how to ever use it—yes, really) or be a straight-up malware scammer type. The problem with those users, if you want to sell them software, is they basically just want/need a browser, MS Office, and perhaps something to play the unorganized folder of pirated MP3s of 50s-90s music the unsophisticated-user side of the family has been passing around for 20 years. They may want something to organize photos and such, but they'll never figure out how to use it right even if you show them how, unless it's high-lock-in, very automatic ("AI" tagging and such), and probably cloud-based (so, likely some Web crap, not desktop software, oh and because advertising and hoovering up user data to train AI is an endless money spigot if and only if you already have massive scale you'll likely be competing on price with "free", so, have fun with that).

> Desktop Linux users are definitely there by choice, yet they too seem to be unwilling to pay for software.

Developing for Linux means receiving support load for all its desktop brokenness (driver problems [mostly video drivers]; issues with any basic hardware+software systems your software relies on to work well for all but the most basic operation, like audio for example; xorg/wayland/DE instability) and every crazy configuration out there.

Sure you can say "fuck off, we support exactly and only [a couple major desktop distros] with the default config that you get if you keep clicking OK on the OS installer and then not changing anything, and only on [list of hardware], report on any other set-up and you will be ignored" but you're already on such a tiny platform that you can hardly afford to annoy/turn-off/generate-vocal-anti-fans-among users. So instead... you develop for literally anything else, or maybe toss out some electron garbage to Linux as an afterthought.

Linux is expensive per-user and doesn't bring you that many users to begin with. Plus, yeah, there may be less willingness to pay for software.