While not everyone likes Windows 10, there are a very large number of gamers that have opted to be somewhat early adopters - or at least get in on the free upgrade so they can spend their money on games instead. According to Valve's Hardware Survey, over 42% of gamers are currently using Windows 10. That's a nice market share and it will only grow from there. Whatever Microsoft is doing with their mobile division, they have at least put their best foot forward with Windows 10.
Steam conducts a monthly survey to collect data about what kinds of computer hardware and software our customers are using. Participation in the survey is optional, and anonymous. The information gathered is incredibly helpful to us as we make decisions about what kinds of technology investments to make and products to offer.