Linux

The nasty truth is, most folks don't have a computer at home anymore. They do everything on their phone. The desktop is reserved for the office worker, which is itself a double-edged sword as the average office worker is so clueless about the computer they're sitting in front of that it could be replaced with a Linux desktop without them knowing anything other than "IT changed this and I don't like it" but the flip side of that is that there's a generation of IT people who learned their craft during the Ballmer era and are now in positions where they run the IT departments (and those who learned before and Linux kinda sucked back then). If they aren't too jaded to try something new they're too tired or too scared of the long term ramifications of trying something so radically different

As someone in the initial "hop around and pick up as many skills and resume line items as possible" phase of my IT career, I've already heard the exact reasons why Windows is still so prevelent "our company's client base is largely farmers. Sure you might have the skills to be a Linux admin but who would replace you whenever you move on? Good luck finding a good Linux admin around here at a rate we can pay!" "Windows Server is so much easier to deploy and troubleshoot without having to remember the commands, why would I bother learning Linux which is much harder to learn when employers around here aren't even looking for Linux experience" and even my friends who appreciate the geekiness and will openly lab out ideas in their free time for fun have to stay realistic about how stable or how janky every part of the given software solution is, plus the value of a support contract where you can answer the "why is this not fixed" questions with "I have a ticket in with the vendor"