I'll update the back of the napkin math since people here can't seem to do it.
First, let's look at the original IDC gaming PC tracker. They've taken this down but a Google cached version is still available. Here it is:
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Let's use the 2021 shipments because we don't have 2022 numbers. Desktop + laptop gaming PCs = 45.4 million total in 2021.
Next, let's look at Macs sold in the latest quarter, Q3 2022.
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Apple sold 10 million macs. Let's assume that Apple will sell 40m Macs in 2022. Let's subtract 5 million from the total because Apple said Q3 was exceptionally good. So we have 35 million Macs in 2022.
Let's assume that gaming PCs did not grow in 2022 (it probably declined).
So we have 45.4m gaming PCs sold in 2022. and 35m Macs sold in 2022. Thus, Macs represent 43% of total computers sold capable of playing AAA games.
tldr:2 years later, back of the napkin math suggests Macs represent 43% of total computers sold capable of playing AAA games. It's not far off from 50%. I think Apple will comfortably beat 50% by year 3 set out in my original post because PC shipments are generally declining while Macs are gaining.