I've recently read a book about the rise and fall of Theranos, the privately held Silicon Valley firm headed by Elizabeth Holmes. The story that author John Carryrou tells in his book, BAD BLOOD, spans the period from the company's founding in 2003 to the lab inspection failures in 2016 that finally broke the back of investor patience with Holmes. As the title of Carryrou's book hints, the story is about blood testing. Theranos sold itself to investors, and in time to retailers, as the manufacturer of a brilliant new machine that was small and simple enough for ordinary people to have in their own homes and use on themselves, that was capable of doing a wide range of blood tests from very small quantities of the vital liquid. It would have been a great medical breakthrough. If it had been real. It was all -- or nearly all -- a sham. At the company's peak, two giant retail chains contracted to sell the miraculous mini-labs: Safeway and Walgreen's. I recomme...