[..] celebrities (particularly, but not solely, movie stars) are always playing a role, even in interviews, etc. When they make a public appearance that isn't overtly as a character, the role they're playing is their "movie star" persona. Unless you are an actual friend of theirs, you don't really know what their true authentic selves are.
Social media, it seems to me, has caused everyone to do the same thing. In social media, people tend to be playing a role -- that role being what they view as the best version of themselves. But it's not their true authentic selves any more than with the celebrities.
I think this has caused a serious degradation in the social fabric. Before social media, the most common interactions you had were with friends and family, and you were mostly interacting with their authentic selves. After all, nobody really knows you until they've seen you at your worst.
Interactions in social media are not like that. You're interactive with people playing parts, and that interaction is no longer genuine human contact. It just has the window-dressing of that.
Loneliness and isolation is the logical result of that. It's a bit like replacing most of your food with "dietary fiber" that is made to look and taste like food. It will fill you up and taste good, but in the end you'll still starve to death.