People jump on the bandwagon of "social media and smartphones are the problem". Most people are sockpuppets, and just repeat this without thought.
If you mean indirectly, then maybe.
I think the problem is late stage capitalism, the increase in exploitation and cheating just to get money, and the real and encroaching fear of fascism or fascism-lite.
Inflation is increasing. Cost of living, housing, food and essentials are rising. Overtime culture is on the rise. Why would I be happy when the outlook for most of us is shit? I have to work long hours just to survive and there's no escape. Buy a house, go into debt for 30 years with the knowledge that the bank is getting massive amounts of free money in the form of interest, and they provide no service other than allowing you to pay an overpriced principal over thirty fucking years.
Work until I'm 67? What's the point? It's time to die at that point as ill be too old and who gives a shit anyway. I'm supposed to be appreciative of my 3 weeks PTO per year, that's when I can go have fun and enjoy life, after that back to working unpaid overtime for a billionaire investor or CEO or whatever.
Maybe social media and smartphones are helping the young see how shit and hopeless our society is. Unless you can figure out how to be a celebrity, or an investor, or a landlord/landowner, you're stuck working a shit job until you're old and life is gone. Why the shit fuck would people be happy and want to have kids?
I'm in my early 30s, so I experienced cooler summers, but also the crises in 2007 and the following years (where basically every Eurozone country south of the Alps almost collapsed).
I also experienced the refugee "crisis" in Germany and obviously covid.
What I learned is, that the only thing our governments can do is throwing money at rich people. Literally nothing else. Every single crisis, conflict, bad situation was met with utter incompetence, corruption, and often enough some new way to blame poor people.
I can't speak for other countries, but ask yourself, what actually changed for the better in the last 20 years thanks to any government action? Rents? Still high. Education? Educate yourself. Healthcare? Here's aspirin, good luck.
The young people of today see that our entire society is moving in an extremely dangerous direction of collapse, and they feel like they can do nothing against it. They feel powerless against a system that ostensibly is super open and democratic. That's why so many (not only young people) are voting for extremists. They want to see everything burn.
I agree with this. Kids, at least middle school to high school, are smarter about this stuff than people give them credit for. I believe this is just kids being given the chance to see how bleak the outlook is for them when before they were not allowed to interact with that part of the world, and when they were, things were better than they are now.
Did things suddenly become worse for those types of things around 2014? If that was the cause, I feel like you'd see a bump up in 2008 with the great recession.
These things have a lagging indicator. You don't see these feelings increase when the problems happen - you see them when people lose faith that they're temporary.