I get that this is probably a joke, but I'll give a serious answer anyways. There are a number of reasons people may choose to use a linux-based operating system, including but not limited to: power user features (many command line utilities are faster to operate than graphical ones), flexibility (basically everything in the operating system can be changed, replaced, or removed completely), security (there won't be any back-doors [government or otherwise] in open source programs because people who review the code will be able to find them), and privacy (linux, GNU, and all the programs they tend to come with are open source licensed which makes all the programs in it very accountable. This also means that it is not a product or something to create money with, so there isn't any kind of information selling. Open source software is free like 'free speech', not free like 'free product'.); all of these benefits have led to many people switching from monetized operating systems to open source ones. There has also been a recent and very strong shift among software companies to start officially supporting linux based operating systems, further driving their usability and popularity.
As for the topic title, you're probably just talking to obnoxious people. Doesn't really reflect on the community at all.
Also, I'd like to page McJob to respond here since he usually has a lot to say about how bad linux is and how everyone not using windows is dumb.
