Zuckerberg has always enjoyed what he calls the « deterministic » nature of engineering—the element of being able to sit down and build something that does exactly what you want it to do. For all the wildly ambitious things he can accomplish as the head of a company of more than 15,000 people that has billions of users across Messenger, WhatsApp, Instagram, and Facebook itself, he missed that pleasurable certainty.

Source : At Home With Mark Zuckerberg And Jarvis, The AI Assistant He Built For His Family | Fast Company | Business + Innovation