take. I would never have expected, for example, that the life expectancy of an American white woman without a high school degree would decrease by five years between 1990 and 2008. I also failed to anticipate how quickly the combination of digital technologies with huge network effects would push the ratio of employees to customers to extraordinary lows. When Instagram, a popular photo-sharing site, was sold to Facebook for about $1 billion in 2012, it had thirteen employees and thirty million customers. Contrast this with Kodak, which had filed for bankruptcy a few months before. In its
