Wow. I still remember when Amazon started as an online bookstore selling books and people kind of laughed at the idea, and the time Amazon kept losing money and refused to post an earning and people got mad. Amazing long game.
As noted by others, the shipping cost-to-item-average-cost ratio is precisely why Jeff chose books to start with. But yes, he also looked way out (even if he couldn't see as clearly as some people seem to think he could).
Though i imagine a lot of reasons justified books.
It's amazing what he's been able to do. Good for him.