I wonder which way the causality runs. Does using too much social media make your life suck, or do you run to using social media when you have a rough life?
Even if the causality runs "life sucks" -> "social media", the effects of turning to social media to deal with stress are different than those of turning to alcohol or comics or D&D or whatever else kids had access to in the past. It's probably worth exploring the effects either way.
For me there is things you do that give you long term satisfaction and things you do that give you short term satisfaction.
I think both have a purpose and a place. However it's inherently obvious that things that are only short term satisfaction and the most dangerous, because you keep repeating the cycle.
For example liking memes is a short burst, a second later they are no longer relevant. For others it's shopping. You get a mini-high, but a few moments later that's gone. A lot of people seem to just keep pressing the button, get a droplet of happiness and press the button more time. That becomes a vicious cycle.
Essentially if your actions today are identical to tomorrow and nothing has changed, you are stuck in a loop. I'm not trying to argue that everyone needs to be hyper-productive all the time. What I'm talking about is if all your hobbies are consumption, you might be stuck.
D&D, which I play is different because you are doing it in a social setting. It's more like socializing with an excuse and a purpose, you get to exercise your creativity, imagination, you are actively using your mind. Passing things like watching youtube all day or drinking don't do that.
Both! Mental illness is quite often self reinforcing outside of the original etiology - clearly so or else it wouldn’t exist as a common meta stable state.
Hell, I'd say mental state instead of illness. Being happy-go-lucky tends to be self-reinforcing in some, or we could use whomever we know that's a "Glass half full" kind of person as our example.