People love making lists, from bestseller lists to favorite novels lists. I am one of the people who like lists. I always go through them before reading any science fiction. Amazon bestseller lists and New York times bestseller lists are among the most widely accepted.
Many years ago somebody made a best of the millennium list! I don’t know how they made that but it was there on the internet.
These lists are mostly related to sales numbers. Amazon lets you write reviews for books purchased from them. They even inform you if they make a sale from your review. The depth of the available lists is breathtaking. Within the Science Fiction & Fantasy category they have sub categories of Fantasy, Gaming, Science Fiction and Writing. Within Science Fiction they have at least a dozen others, from Cyberpunk to Time Travel.
People like myself need others to inform them about what is being read. Lists are a powerful way of doing that. Writers, publishers and book sellers figured this out a while ago. This is the reason why they mention this on book covers. Many books say ‘New York Times Bestseller’, Hugo Winner or Nebula Award Winner.
Self publishing is a good way for authors to publish their work and get on bestseller lists. This allows them to remain independent of old school publishing houses. Publishing houses tend to have the upper hand because they control the whole process from selecting what gets published to getting this stuff to the readers.
Quite a few science fiction books on the Amazon bestseller list are from self published authors. A great example is ‘The Atlantis Gene’ by A. G. Riddle. If Riddle would have had to go through a publishing house, chances are that he might never have published. We would have missed out on such good science fiction and Riddle would probably have had to change his job to a store clerk on something!