Hmm, that could be an attempt at bonding over a common enemy? Kind of like talk bad about the boss behind his back, so that you bond woth your peers? Generally not for everyone, but could see how people get fixated on it if it works for them. Or maybe they are just caught up in the negative media and it has a big effect on their overall mood. Do the happier countries you mentioned have less reliance on media? Again, negative generates views, thats why the news is usually mostly bad.

I think this is a classic case of “The complainers are way more vocal than the life enjoyers”, combined with modern technology being set up to promote controversial content. When someone’s enjoying this life and being chill, they also don’t usually care about spreading thier message. The complainers are either memetic or often political and seem to enjoy a much greater platform. Also more controversial content generates more negative engagement, and most social media promotes content that has high engagement, because it benefits them to have users engage and stay on the site longer.