Have you browsed Amazon's "best seller" lists recently? Noticed they're basically useless? Brent Underwood shows why there's so much useless junk on there (tl;dr people are exploiting the system to bolster their personal brand).
A while ago, I put up a fake book on Amazon. I took a photo of my foot, uploaded to Amazon, and in a matter of hours, had achieved “№1 Best Seller” status, complete with the orange banner and everything.
How many copies did I need to sell to be able to call up my mother and celebrate my newfound authorial achievements? Three. Yes, a total of three copies to become a best-selling author. And I bought two of those copies myself!