Google is still reaping its fruits from the early 2000's investments in a new browser that was lightweight and stable but had powerful search and apps, unlike the default browser of MS. So at that point in time people deliberately installed chrome on their PC since the default did not fulfill their wishes.

That doesn't mean that people today are choosing chrome and google search, as they come by default on their smartphones. Most smartphone users don't even know that the browser and search engine can be changed rather easily.