Emotions in Sharing Content
Content than make you emotional are more likely to be spread/shared.
The best emotion to get you to do things is anger. Anger bypasses the mental "immune systems" and gets you to act faster(think Amygdala Hijack).
These ideas will go thru a mutation process. The one that pushes your buttons will get spread more. It doesn't have to be true. Over time, with multiple shares, it gets tweaked to be more efficient at making you angry. Every time this happens, it moves further from the truth.
Generally this will reach a saturation point and dies out. But there is a way for it to survive longer - meet a similar idea on the other side. That will make the people fight longer. The two opposing ideas are in a symbiotic relationship.
Once this happens, each side will create their own idea of how the other side is. That idea is what they fight against. This could be very different from what the reality is.