...large, diverse, secular democracies are inherently unstable, inherently prone to division unless there are sufficient “centripetal” forces pulling toward the center (such as having a shared language, shared rituals and values, and high trust in the basic political and economic institutions of the country).
Facebook and other social media platforms are powerful centrifugal forces, binding groups together to fight other groups within their own country, driven mad and propelled into battle by an eternal mudslide of outrage-inducing viral videos and conspiracy theories. We are already seeing these effects in many countries.
I predict that by 2030 we will see the spectacular political collapse or geographical division of more than one Western democracy that seemed rock solid on the day Facebook was founded, 15 years ago. My hope is that people, societies, and governments will find ways of adapting to or regulating social media that will render my prediction wrong.