I use both equally plus I have a Mac so it doesn't bother me one way or the other what runs on what, I have all avenues covered. :hehe:
However.
Did the other minority OS users contribute as you are suggesting? Mac users are also a minority.
Linux users would, the same as Mac users pay for the development by purchasing a version of Trainz for their chosen platform, point being I don't think there are enough people who are that interested in a niche hobby like railway sims that use Linux to make it profitable.
Why Trainz on Linux? Because it is an operating system that has been around as long as Windows and millions of people use it, not as many as Windows granted but still a large number
and in a free world they are quite entitled to ask that their chosen operating system is supported. It probably isn't likely to happen unless Microsoft suddenly shuts down though.
Why use Linux? Personal choice, No need for antivirus programs anti malware programs and daily updates or if behind a router a firewall, so long as you stick to the rules and don't run as root, a Linux kernel has inbuilt security features. An operating system that only require around 4GB of space yet can perform all the functions that Windows can using it's vast resource of free programs. You can also easily customise your desktop to use whatever window manager suits you best, you are not stuck with one choice as in Windows.
Android is based on the Linux kernel, 99% of routers use Linux, navigational aids, NASA, Quite a few governments, Many webservers are Linux, think N3V's are actually. Facebook uses guess what? Linux, Googles servers are, yep Linux again and of course YouTube is also on Linux.
Many Linux programs have actually been ported to Windows, Blender was a Linux application still is, VLC is a Linux program, Open Office is a Linux developed program these probably would never have made it to Windows if there was no Linux.
Linux may not be mainstream in home computing but it certainly isn't insignificant.
The only thing that keeps linux from having to fight viruses, is that virus creators go after the most popular OS, ( windows) which gives them the largest target. If Mac and Linux got to the same popularity as Windows, they would experience the same potential for virus attacks.