Because nearly none of the software I use daily is supported on any of the BSDs. Don’t get me wrong, I have fun playing around with them, but I’d be miserable using it daily. I still have to switch to Windows every now and then, typically for a game that a publisher refuses to have their anti-cheat software run on Linux (as well as a few other one-off situations.)

Because it’s Microsoft and whether anybody likes it or not, they’ll do whatever they want and at best, lose a few pennies.