...in 2019 Facebook boasted nine times the users, 21 times the revenue and 12 times the profit of Twitter (see table). More importantly, the strong network effects are a prime asset that Facebook has defended vigorously: it has spent vast sums on buying firms it considers likely future competitors, such as Instagram, acquired in 2012 for $1bn, and WhatsApp, for which it paid $19bn in 2014.