Mainly for development purposes. I plan to use the Steam Machine as my new travel PC and for my work on OpenRGB I want both Linux and Windows for testing. I use Windows to reverse engineer the official software and protocols for devices so I can reimplement them in a cross platform way to work across all OSes. Also maybe for Fortnite, the only game I still need Windows for, though my friend group hasn't been playing lately, I know how to fix the bootloader, spent time getting a customized rEFInd config going.