People can only inhabit a finite number of social media networks, and there can eventually only be a fairly small number of big players in a position to produce massively detailed rich profiles on individuals and therefore hold most influence on them (consumer behaviour & voting behaviour)
Imagine that the USA clamps down heavily on facebook, and in 4 years some rival company from Russia or China ended up achieving the largest market share / richest per-person psych profiles. That represents a security threat even greater than the (nearly catastrophic) threat that Facebook represents today. Who wins and who loses in this race is going to make a massive difference in what the planet looks like 20, 10, even 5 years from now.