Stefan Mileschin

Windows 7, however, is still the dominant OS of choice when you include 32-bit users. Windows 10 64-bit has finally overtaken Windows 7 64-bit as the most popular operating system for Steam users. While many people would assume that the majority of PC gamers would have immediately switched over to Windows 10 on account of its free upgrade path and general lack of downsides, the Steam community has been fighting it for a long time. Many Steam users felt that they couldn't trust Microsoft anymore after their rejection of Windows 8, and so they backed into Windows 7 with an "if it ain't broke, don't fix it attitude."

http://www.hardocp.com/news/2016/04/...es_7_on_steam/