Like so many before you, you are making the mistake of thinking Apple cares about marketshare.
They quite demonstrably don't. They care about profit-share, and about making what they see as the best computers they can.
As others note, Apple already takes either a plurality or a majority of the profit in computer sales. What incentive is there for them to reduce their average margins, take on a lot more support responsibility, and have to ramp up production significantly, just to capture a notoriously fickle and unrewarding segment of the market?
I actually thinks Steve would actually lower the price of iPhone and Mac given how profitable they are now and how much cash they have. Instead of Doing Shares Buy Backs.
>What ruined Apple was not growth … They got very greedy … Instead of following the original trajectory of the original vision, which was to make the thing an appliance and get this out there to as many people as possible … they went for profits. They made outlandish profits for about four years. What this cost them was their future. What they should have been doing is making rational profits and going for market share.”
Just look at the BOM cost of MacBook Air and an iPad Pro. There is not reason why MacBook Air cant be $799.
What competition? Just like with phones, Apple is already getting most of the profit from computers. The commodity PC market is not exactly one worth going after.