For about 12 hours on September 26 and 27, books I'd written were the #1 and #2 bestselling Horse Books on Amazon.com. (Geoff's was #1, Clinton's was #2.) It was a rather surreal experience to see onscreen.
Other cool numbers that cropped up showed that Geoff's book ranked in the Top 10 of Individual Sports titles, and in the Top 35 of all Sports titles. Its overall ranking for the nearly 2.5 million books available on Amazon.com was 1960-something. It may even have done better than that, but those were the numbers I saw.
It's never a good idea to put too much credence in bestseller statistics. From Amazon.com to the New York Times to other book trackers, the titles on such lists vary from week to week and from day to day. A book may hit #1 on one list and not even register on another. Playing the bestseller / numbers game can really mess with your head.
On the other hand, having a title reach #1, the Top 10, or even the Top 100 of a bestseller list can add a certain amount of cache to the book. It can help generate some "buzz" (a loathsome marketing term) and give the project a continued boost. The term "bestselling" can also help validate an author's efforts and be used to gild the writer's bio.
Aiming for #1 is hardly a reason to write a book. On the other hand, it makes no sense to put forth the time, effort, and energy necessary to create a book if you don't believe in the project enough to be willing to promote it as best you can.
I am fond of reminding writers: No one believes in your career more than you do. If you don't believe your book deserves to be a bestselling title, perhaps it's worth revisiting the project and perfecting it until it's clearly the best thing for readers to do with their money and their time.
I tell all new (and not so new) authors to go for it. Aim for #1. Come up with a plan and put it into action. The danger is not in aiming for the stars. It is in failing to raise your sights to the sky. It is also in believing that you're too good for this world.