I'm a father of teen kids, teacher and educator. I don't think that there is a single reason here. All mentioned things contribute – social media pressure, climate problems, economical crisis etc. But I'd like to add another one – declining quality of education. I see increasing number of teens depressed because they don't have teachers and their education isn't good enough for jobs they'd like to get in future. And…
There's also been a corresponding dramatic drop in the number of teens who have had any sort of job. Not many things are as fulfilling as doing a job and getting paid for it. I remember when I realized I was making enough money that I could pay all my bills and no longer needed anything from my dad. It felt really good. For me that was the dividing line between being a child and an adult.
When I was a kid there was never a time when I could pay for everything. The first time that happened was an internship I got during college, and then my first job right after.