Because OSX provides a reasonable middle ground between usability and control. You can use it as a regular user when you want to do things like listen to music,

Because OSX provides a reasonable middle ground between usability and control. You can use it as a regular user when you want to do things like listen to music, watch movies and browse the Internet, and you can also use it as a "hacker" by leveraging its "Unixness". It also integrates extremely well with other parts of the Apple ecosystem, unlike Linux.