Two things I think explain JKR, first is just the social media rot. Basicaly I do agree in some way that humans have not particularly evolved to handle social media at this scale. It takes a lot of effort to handle being famous, unironicaly between the love and hate, not attaching yourself too much to either side, not letting the reception of the work define your personality too much etc. But that is just one side.

You’re hunter gatherer, you say something stupid you get hit in the face, you’re living in ancient civilization or whatever 5000 years ago you say something stupid maybe you get on top on a bucket and shout, maybe 20 people hear you call you names and throw a rotten fruit on your face as you run away. Today you get on your soap box, say stupid shit and instead get anything from 2k to 2million reply guys saying “yes boss”, “totaly correct sir” etc and the hate you’re supposed to endure or force you to reconsider, you can selectively block away.

IMO If people in the ancient world could get on a soap box and speak for the entire city of e.g Rome at once and not get a single reply that makes them uncomfortable enough to self reflect then we clearly wouldn’t be here as a civilization today, shit would have burned down thousands of years ago.

Second if you look seriously deeper this is a problem with “success” for a lot of artists/creators. They get rich and famous, they’ve created The Thing and then they have this void. Some turn to drugs, others to gambling while others just have a “normal” life. I think the most stable group tend to be the ones who still manage to fullfill themselves with their work. JKR clearly doesn’t get much out of working anymore imo so social media drama-attention farming is all she has left in her pitiful life.