Leaving as billionaires, they have emanated Silicon Valley’s relentless positivity. Pinterest “is just getting started,” Airbnb “is in the best hands it’s ever been in” and Instacart has a “enormous opportunity ahead,” the founders wrote. Both Mr. Mehta and Mr. Gebbia said they had plans for new projects.
Investors say they anticipate more of these resignations from founders who are realizing they now have to work harder for…