Most people grew up using windows. Familiarity has a huge part. Why isn’t everyone using macos?
Very different questions though. Linux offers massive and plentiful advantages over both of those.
I am not disagreeing with the familiarity idea, though; change terrifies most people.
A lot of people just need to get shit done and it’s easier to just use the tool they know than to relearn how to use a computer.
I think relearn how to use a computer is a real stretch. Like colossal. Plenty of distros and DEs make it even easier than Windows, can look exactly like either, and are far less accident prone.