You’re assuming a level of insight into people’s meta-knowledge of their own mental state that I don’t think is warranted. Maybe they’re not thinking of social security, but maybe there’s mental health benefits to caring for elderly grandparents at home that people don’t appreciate.
As to leisure—in the 1950s, half of 16-19 year olds had jobs. Today it’s around 30%. Maybe having a real, if menial job is more fulfilling than playing video games or doing bullshit box checking exercises for college applications? That’s a cultural change too.
I'm guessing fewer 16-19yo have jobs mainly because school is more important now. College attendance is way up.
If we're going to make random stabs in the dark and bring in our own bargain basement personal opinions into this, I can tell you at least that interacting with my abusive family much less has only been fantastic for my mental health. Obviously this isn't the case for everyone, but maybe that's not important and I should just universalize this viewpoint like you, right?
I can almost guarantee that young people don't have social security on the top of their minds. It's school school school internship work, that's it. Those bars are raised each year. Leisure time is social media and video games. All that got amplified in 2020. Not hard to see why they're depressed.
[Edit] I was standard college undergrad class of 2018, and right on the cutoff for gen Z. Our high school and college class was very clearly more studious than class of 2016, and very clearly less than class of 2020. I was also right there when childhood became virtual, starting with the iPhone and Facebook.