Most computers you see these days are running the crappy Windows OS made by Microsoft.
Windows OS is a closed source operating system, meaning only the developers in Microsoft are able to see and make changes to the source code. While that means only they can sell it, it also means that there are more issues that are overlooked, which an Open Source OS fixes. Even operating systems that aren’t completely open are generally more secure. Take Chrome OS as an example, the OS chromebooks use, that’s based on chromium OS, which is open source, so there are many more developers that can improve it.
Windows is way less secure than it’s alternatives, and I don’t think that’s really because of its market share. Windows is just less secure, and it’s easier to install programs in the background without the user’s knowledge. When I had a Windows computer, I must have installed a hundred viruses. With all my time on Ubuntu, and Debian I’ve encountered zero viruses, even though I use Linux much more. I also think that it’s because many Windows users have an Admin account, whereas on Linux, you need to login, and then type your password yet again to run a command as an admin(root), making you think about what you’re doing more.
Windows costs at least $100 for the software itself, not including a computer. While many computers already come with Windows, nothing beats good old free Linux distros. On top of the fact that you pay nothing for the software, it also requires much less resources, meaning you can get the same experience on a cheaper computer. Some enterprise distros offer payed versions, but that’s generally for support, or for extra features. There’s also no annoying license keys to deal with. For example, you can get a chromebook for about $150, that will feel much faster than a $200 or even some $300 Windows laptops!!
Windows generally needs to reboot once a week for updates, and that’s assuming it never crashes, which it does. Linux, on the other hand, is capable of running for not days, not weeks, not months without a reboot, but can go for years without rebooting, all while staying secure. That is largely due to live kernel patching, which allows for kernel vulnerabilities to be patched without a single reboot.