True, but you're still wrong :) In 1997 Microsoft bought $150 million of non-voting Apple stock, which IIRC was about 5% of outstanding shares. They sold them a few years later for a rather large profit.
So MS doesn't currently own any significant share of Apple. But MS still makes a bundle on Mac Office. There is no particular reason for MS to fear Mac market share.
When others drool over Apple products, I buy Apple stock. My wife is getting on my case to sell my Apple stock shares, as their price is going through the roof and I had bought low. It's cyclic, every couple years buy low and when they have new products it goes up and then sell. Apple makes me happy in this way!