7 bucks, 2 hour read, helped someone go from a poor, rural, single parent upbringing to the top of his field. Sounds like a no-brainer. Ordered it.
Did it really? I seriously doubt it. Bill might be mistaken. To me it looks like just one of the cognitive biases: http://en.wikipedia.org/wiki/List_of_cognitive_biases
Unfortunately we cannot conduct an experiment of having two identical Bill Clinton, one of them read this book while another did not, then see they results.
But among more than 3 million of book readers, how many of them have something as close to Bill Clinton's achievements?