Certainly part of it is mental health. No Question.
I also believe a major reason is this ungodly sense of entitlement most Americans have, and one I struggle with myself. Instead of the earlier days when we were focused on learning, doing our job at the best of our abilities, and striving to make this country greater, we are now more worried about our feelings, emotion, and instagram likes. People's sense of self has changed and seems to have made a lot more people who are just mentally fragile.