Facebook paid an unprecedented price for WhatsApp because mobile messaging threatened to become the primary social layer on smartphones. The deal looked extravagant in 2014, but WhatsApp became a core part of Meta's global product family.
Facebook spent tens of millions redesigning servers and data-center infrastructure, then gave the designs away through Open Compute. The counterintuitive investment lowered its own costs while helping create an open hardware ecosystem.
Facebook's Instagram purchase looked extravagant in 2012, but it bought a fast-growing mobile network at exactly the moment Facebook needed to prove it could win beyond the desktop.
Microsoft’s $240 million Facebook investment bought a small equity stake and an expanded advertising alliance, producing financial exposure to social networking without giving Microsoft strategic control of the platform.
Accel’s $12.7 million 2005 Facebook round financed hiring, infrastructure, and expansion while the social network was still concentrated on college campuses.