Then last February, Facebook agreed to pay $19 billion for the fastest growing of these apps, WhatsApp, and many people understood it to be Facebook’s tacit recognition that Messenger didn’t work. The services, however, had very little overlap. Most of WhatsApp’s 450 million users were overseas, and they took to the app to get around paying for pricey telephony plans. Meanwhile, in the lucrative North American market, Facebook was still behind. That’s why Zuckerberg invited Marcus to dinner. A serial entrepreneur, Marcus, 41, sold a payments business to eBay’s PayPal in 2011, and soon after, he became CEO. This appealed to Zuckerberg. With Instagram’s success, Facebook had proven it could buy a startup and nurture it, allowing it to flourish while benefiting from the Facebook-size resources—legal and infrastructures and spam prevention—that go with building a billion-person service.

http://www.wired.com/2014/11/on-david-marcus-and-facebook/