Few can measure the impact of a blog post they wrote, in the millions of dollars a year, but Patrick McKenzie has the receipts. His 2012 post on salary negotiation is read hundreds of thousands of times each year, and he has a Gmail folder brimming with success stories. This achievement is just of his many contributions, which include starting several businesses, advising Stripe and other software companies, and spearheading the launch of VaccinateCA. Lately he’s been writing Bits about Money, a...