Not that I care a whit about this argument, but sales figures alone do not denote the number of people who read a book--or the number who thought it was good/excellent/deserving of an award. Sales can be an indicator, but I can testify as a publisher that we authors need a certain number of sales from habitual BUYERS who actually rarely read because hitting that group is very important to rankings and continued visibility.
A popular book being talked about can be a self-perpetuating success--people buy products for many reasons and one of those reasons is to be in the "in" crowd or because the product is familiar to them--they have heard of it, it must be good/quality.
As reported by Kobo in the "How far do people read" thread--note that Gone Girl sold millions but by one metric, was only finished by 40 percent of buyers.
https://www.mobileread.com/forums/sho...d.php?t=255556
So while sales is one metric, it is not necessarily a good metric for "this book is good/great" which is why there are awards like the Hugo, etc.