In PC gaming, Windows 10 is 38% now. It's more than Windows 7. PC gamers prefer Windows 10 because of DX12. See in Steam.
http://store.steampowered.com/hwsurvey
You mean in "Steam Gaming", Steam is not all PC gamers.
Also, Steam defaults to "Windows lastest version" in some situations (example: the stats for game purchases by platform, count as lastest windows when you buy using mobile)
Also Wine counts as Windows.
Finally, you forgot to count the 32 bits versions of each OS.
Win10 64+32 is 39.51%, Win7 64+32 is 39.54%
And for a dev standpoint, going exclusive DX12 now would still be a stupid decision, if you look in the "DX graph", you will see that only 33.52% has Windows 10 AND DX12 GPU at the same time, meaning a DX12 exclusive game would lock itself to a minority of the market.
Also, Steam defaults to "Windows lastest version" in some situations (example: the stats for game purchases by platform, count as lastest windows when you buy using mobile)
Also Wine counts as Windows.
Finally, you forgot to count the 32 bits versions of each OS.
Win10 64+32 is 39.51%, Win7 64+32 is 39.54%
And for a dev standpoint, going exclusive DX12 now would still be a stupid decision, if you look in the "DX graph", you will see that only 33.52% has Windows 10 AND DX12 GPU at the same time, meaning a DX12 exclusive game would lock itself to a minority of the market.