The last great holdout for windows was games. For office stuff, the transition from monolithic AD/Exchange stacks to cloud based stuff made Macs a viable platform for many organizations, particularly with software devs finding the Unix system under the hood productive for developments meaning that while Sysadmins have traditionally been mac hostile, devs are often mac friendly (well, other than the dotnet guys), and with the corporate drones enjoying the user friendlyness and fashionable appearances of the machines, windows centrality to the office has been under serious challenge.
But games where unchallenged. While modern macs are respectable for games that have been ported, its undeniable that windows was clearly the winner in this field, with access to Nvidia (and increasingly AMD) GPUs and APIs well suited to gaming.
But Valve has different ideas, and despite the attractiveness of the XBOX subscriptions, Valve have a near monopoly on the ecosystem, and Valve do NOT like Microsoft breathing down their necks. So proton (A wine fork that works shockingly well) has been under constant development and is now at the stage where many windows-only games run as well, if not better, under Linux, even on small machines like the Steamdeck (I have one at home, and it runs..... every game I've tried. Oh and with the emulation stuff makes a pretty great nintendo switch emulator too)
So yeah, the final fortress in windows dominance has toppled. Linux is just a straight up better server. Macs are viable and friendly. And now Linux even plays games better, or at least competitively.
And with Microsoft hell bent on turning windows into a hellscape of chatbots , corporate surveilance, subscription slop and advertising, people have had enough.
If Microsoft doesnt change its ways, its going to lose everything its worked for.