It's worth noting that the percentage of Steam users that are Mac users is not going to be equal to the percentage of gamers who play games on Macs, because not only is Steam not the only distribution channel for games on Mac, it's always been a fairly poor UX there, so bad I don't usually even bother installing it on my Macs anymore. Steam sees me as a Linux user as I have a Steam Deck, but I spend more time playing non-Steam games on my Mac than I do using that.

Actually, I think the last time I installed Steam on a Mac I did so in a CrossOver Games bottle, so even there Steam would have seen that install as a non-Mac user.

EDIT: Also just because I think it's interesting to note this, Steam Deck accounts for most of Linux's headroom there, if you subtract the SteamOS numbers from the rest of Linux it's at 2.07% instead, which is much closer to Mac.