Even if the sales numbers translated to a 80%-20% laptop/desktop factual usage worldwide, and it doesn't, we wouldn't "all" be on laptops. Other than that being irrelevant to the fact a mouse is being used or not, much less what kind it is. Actually I am on a dual desktop and sometimes on a renderfarm, sometimes rendering content with parallax in it.
The parent post made a comment about not having two finger swipe. The comment I replied to asked about the scroll wheel on his mouse, which assumes he has one. I replied that most people are on laptops; laptops do not require mice, so it's not a given that he has a mouse at all. Saying most people are on laptops is not the same as saying nobody has a mouse.