Confirmation bias or the tendency to interpret new evidence as confirmation of one's existing beliefs or theories. We believe what we want to believe and anything else, well, if it doesn't fit into our sphere of thinking, it's bad. It's almost like a mob rules. We saw it in pre-WWII Germany. The power of suggestion then moves into this backfiring.
I have witnessed this first hand when a guy I know tried to explain alternative facts to me. So I googled the definition of 'fact' and showed him... That was not good enough.
Absolutely not facts to back it up but my belief is the internet. We all now have a "voice" across the globe and we want our opinions heard. While social media has brought us together like never before, it has divided us just as much. There was a post here on how everyone is now an expert and this falls right in line with this unfortunate trend.