Why are we all so anxious and stressed? Is there something very wrong at the root of our culture that is causing us to be like this?
Yes. Our culture is unnatural, by which I mean we have evolved way beyond the point that anything we do can be considered the natural way of things.
We don't hunt, we don't fight. It's actually illegal to do those things - try killing and gutting a deer, or taking your neighbour's home away by force and you'll be in a lot of trouble very quickly. We don't work for ourselves, we work to make rich people richer. (Medieval peasants were freer than we are, they had to work for landowners but proportionally they kept more of their labour than we do now with the tax system.) Nobody knows what's really true anymore because we are constantly lied to from all points on the political spectrum. We celebrate the most unnatural, we promote unnatural behaviour whilst simultaneously complaining that we are ruining the planet. Equality is unnatural, while slavery is one one the most natural institutions going. Up until a couple of hundred years ago pretty much every civilisation enslaved people and treated others like shit.
(Before any reports me: I'm not saying equality is wrong and slavery is right. I'm just saying that if you look at the whole of human history equality is not a natural state whilst slavery is.)
The problem I think is that humans have overstayed their welcome on the planet. I think that we have evolved too far and the planet is no longer suitable for us. Either we need to drive ourselves to extinction or create technological solutions so as to enable us to live freely without worry.
Personally, I think the post-WWII cold war period was the point at which we should have nuked ourselves out of existence. Humans usually find the ability to destroy and kill to the maximum extent allowed by the prevailing technology. With nuclear weapons, we finally created enough firepower to destroy all human life and arguably the natural thing to do would have been to follow through on it.
Anything that follows on from our failure to blow ourselves to smithereens is bound to cause anxiety on an epic scale precisely because we have failed to follow human nature on an epic scale.
As a side issue, this is why the whole Extinction Rebellion movement is so ridiculous. Species have come and gone throughout history, it is natural that humans will (and should) suffer the same fate. It is incredibly arrogant to assume we're better than every other species ever so deserve to live on indefinitely. Above all, it doesn't matter in the slightest whether we make ourselves extinct tomorrow, or in a million years from now. If not now, when?