The printing press led to more than a century of religious wars in Europe, perhaps even deadlier than WW2 on a per-capita basis.

20 years ago we all thought that the Internet would democratize information and promote human rights. It did democratize information, and that has had both positive and negative consequences. Political extremism and social distrust have increased. Some of the institutions that kept society from falling apart, like local news, have been dramatically weakened. Addiction and social disconnection are real problems.