I would argue that the cause of the "Fake news" epidemic is partially due to the social media. Specifically, Information Overload is to blame.

A few decades back we had and now loosing: - Traceable reputation -- which is now lost, and much harder to learn in our uncontrolled, random and sparse feed interactions. - Focus on topic -- social crises were build up, considered, reflected on. Nowadays, we moved into the realm of emotional reactions. Noone is expected to have mental capacity to consume as many pieces of disjoint information as we do today on social media. In an average feed, a president eats a kid, and a cat does a funny trick one after another.

The prime incentives in the current social system is the instant gratification. This new system is easy to abuse, as we are moving further away from analytical to emotional consumption.