Not all of us run Windows. I used Linux through my whole degree. Luckily my CS program was very good about very rarely requiring closed source or windows only software. There was only once, for some software engineering course, that I had to go down to the lab and use their machines. I think the homework was required to be done in Visio or something like that.
Definitely see your point. During my time in college I only used Linux also. Now I work for a niche company where using C# allows us to get a lot done very quickly for the size of the company, and it's efficiency for getting stuff done is amazing. I love how great it is for completing stuff, but does suck not being able to use on any platform.
That being said unless it's just a quick hack for myself I tend to stray from C# due to it not being usable on all platforms.
