What growth are you talking about? Is there an actual research, that indicates that number of flat-earthers have grown compared to previous decades?

And why do you think, that there is a relationships between flat-earth nuts and social media, as opposed to, say, HIV, cancer and other diseases and social media? Social media made you more aware about flat-earthers than before, but it didn't turn you into one.

Then again, the same way people can become aware of the problems with their political system through the internet. I understand this has happened in Syria within the last generation or so.