Well, Amazon sells many items as you may know, and not just books...many items having a magnetic attraction to my credit card, causing it to vibrate in my wallet, telling me to "buy now!" In my pre-Kindle days, I rarely bought anything from Amazon, other than an occasional hard to find book, or electronic gadget. What prevented me most of the time from buying on Amazon, was a need to have to walk upstairs from my home office where I was online, to retrieve my wallet and credit card to complete any purchase I might be contemplating. I usually decided to consider the purchase at some other time when I might have my credit card handy.
With the Kindle came an introduction for me to Amazon's electronic bookstore. Also, Amazon realizing there are many people like me who are too lazy to go and retrieve their credit card to make an immediate purchase, cleverly created the "one-click" buy button on their webpage. Enter your credit card information securely one time, and presto from that point forward you never need to have your card handy again. Talk about instant gratification, and since you never have to actually get your credit card out to enter all the digits, it's almost like you're not spending any money...almost.
I recently got my first credit card bill since I bought the Kindle. I was surprised at first when I saw the balance. Then, I remembered "one-click". That neat little Canon desk top photo scanner I saw on Amazon on day while looking for an ebook was on my bill, as were several other non-book items...like a new pair of 5.11 tactical pants. And then of course, I had purchased several eBooks for the Kindle, since I needed something to read.
Got to give Amazon credit, they sure know how to sell stuff...at least to me. And, all with "one click".