I think it mostly comes down to increasingly unfair distribution of wealth, which leaves people with no hope to better their standards of living.

Our civilization creates things with constantly increasing productivity, which should lead to better pay and less time spent working, and more time to live a fulfilling life. Instead, all this added wealth is funneled towards a few mindbogglingly rich individuals.

This happens with the help of a sizable fraction of the population, which has become convinced that their mediocre situation is in fact caused by even poorer and more miserable people, rather than the assholes siphoning everything and everyone from the top of their already obscene piles of riches. And there’s no sign of this changing anytime soon. No wonder people are desperate.