Dave Hitz likes to solve fun problems. He didn’t set out to be a Silicon Valley icon, a business visionary, or even a billionaire. But he became all three. It turns out that business is a mosaic of interesting puzzles like managing risk, developing and reversing strategies, and looking into the future by deconstructing the past. As a founder of NetApp, a data storage firm that began as an idea scribbled on a placemat and now takes in $4 billion a year, Hitz has seen his company go through every...