Don't mean to sound deep and profound here but I think life in general damages your mental health. Social media just brings it to you in a superficial format.
But I do also believe those little notifications can be addictive.
That's very cynical. It's possible to enjoy life more and more as time goes on. Read Triumphs of Experience. My dad is one of those lucky people.
Besides, even if life itself /is/ damaging in general, that doesn't explain the teen suicide rate etc, or any of the findings from this report specifically pertaining to teens.
It's more a case of happy people and unhappy people being largely unable to understand each other and then turning their general outlook into a theory of the world. Even a single person can have trouble remembering their own happiness when they sink into depression and their past pain when they are breathing life into their lungs.
I don't think markets and mental health are quite as intimately related. I think it's more to do with living in an individualistic society where we have less of a social net to fall back on. And I mean 'social' as in a close-knit community, nothing political.
But I do also believe those little notifications can be addictive.