one of the most comfortable eras of human history
And that is why people have more time to contemplate over the meaning of life and focus on their emotional and spiritual needs, yet most of the time these needs are not met due to the mechanical routines, atomization, individualist culture, decline of religion, etc.
People who are financially stable lack motivation and energy after trying to sustain the current life to pursue anything besides short-term entertainment that would just pump the dopamine immediately, while those who are struggling to maintain a comfortable life no longer believe in the libertarian propaganda that hard work always provides rewards and are filled with resent towards those who are born in more fortunate circumstances.
But both groups have a common enemy, which is the "current system". What is the current system? Who controls the current system? How does the system work? People with different ideologies will give out different or even conflicting answers. We might not have a collective meaning, but at least we have a conceptual collective enemy to blame on, whether it is capitalism, cultural hegemony, fate, domination of technologies, or whatever. Individuals are believed to be powerless or trivial within the system, which only contributes more to the existential crisis.
anti-natalism and the rise in pessimism
They overlap a lot. Both of them also tend to be convinced that they are the logical and rational ones who can see through the reality while the inferior others are manufacturing false purposes to cope, but that might be more nihilistic than pessimistic. It is not surprising to see an outburst of these ideas when everyone reasons that we are living in a dystopia.
Or...it might just be those damn microplastics poisoning our brains.