Personal anecdote, and not about social media per se but the infinite-wall aspect of today's web, made my brain behave in very scary ways. I had a few times where I didn't order my hand to swipe (because I was expected to do something else right away) but my hand swiped. It was sufficiently against a part of my mind that it felt 'not me' and it happened a few times, sometimes even more complex movements.

To me it's an evidence that the brain is that sensitive to neurological reward to the point of being bent into automatic aimless actions just for the sake of keeping the cycle going.

It's not as deep and harmful as alcoholism but still too large not to ignore.