In 2013, when it was revealed that a developer was planning to purchase one of the four properties next to Mark Zuckerberg’s Palo Alto, Calif., home, and pitch potential buyers on the idea of living next-door to the founder of Facebook, the 29-year-old multi-billionaire purchased all four residential properties and leased them back to their current occupants, whose neighborly discretion he valued. Businessmen do business to make money. But occasionally, as Mr. Zuckerberg found out firsthand, business ventures have human costs. In a 2013 letter to President Obama and congressional leaders, more than 100 tech executives, Zuckerberg among them,...