A: Just an educated guess here…
Every business, to be successful, must differentiate themselves from the competition.
An obvious differentiator to use is security and privacy. MS has a long history of paying little attention to security and privacy. This makes it easy for a competitor – particularly one with a history of having better security and privacy (Apple) to fill that niche.
Now with that differentiator in place, a potential buyer needs to make a decision as to what product to buy. They can weigh price, features, availability, stability, appearance, performance, compatibility, AND security and privacy.
If security and privacy are more important to the buyer than other issues, they will likely go with Apple.