I'm sure there are exceptions. Nonetheless, something like 80% of the PC market overall is Windows.

it's not really windows marketshare that matters - it's the instruction set. x86 compatible instruction set is dominant today.

If apple really want to disrupt intel (and i guess by collateral damage, AMD), they will release the m1 CPU as a commodity. but they will also have to figure out how to get microsoft to play ball as well (which i am not sure they will).