Let us not forget the massive contribution of Richard Stallman and GNU. Linux was developed as a kernel, not a complete OS. Regardless of Stallman's unsavory politics and personal style, his GNU software and licensing were absolutely critical to the success of Linux as an OS, and comprise the majority of the "Linux" OS software currently in use.
#8 Windows and OS X are malware, claims Richard Stallman
http://www.theregister.co.uk/2015/05/25/stallman_windows_and_mac_are_malware/