I don't think most of us realize how we are hardwired to live in doubt and despair. It's because thousands of years ago one bad decision could end your life very quickly and we were only one meal away from malnutrition and/or starvation. The interior of the human organism hasn't changed much over the last 5 thousand years, but our external circumstances have changed dramatically thus throwing many of us into a confused, and often contradictory psycho-emotional state of disequilibrium. Modern electricity, antibiotics, and having parents who protected us and provided for us 24/7 for the first 18 years of our lives has made our tolerance for suffering and uncertainty very low. And so is it any wonder that with so much extra time on our hands because we don't have to go fetch water or try to hunt and kill an animal for dinner tonight that many of us are over-consuming and over-analyzing both the domestic and global (((news))) cycles, and that this is making many of us depressed? Our brains can only handle so much localized information, we were not built to take in the world's problems and information and therefore many of us are experiencing a chronic sense of depression via sensory overload.
Due to their environment, namely good parenting, and having abundant resources (i.e. money), some humans grow up fully functioning and are naturally optimistic and happy. They were taught that "life is good," and that "the world is your oyster," and they therefore made it such. However, many more of us humans were neglected, and beaten, and told we were worthless, and we came from nothing. Or we lived in a house of uncertainty amongst married people that barely tolerated each other and were constantly on the verge of divorce. And so individual experience varies depending on a host of biological and environmental factors. Some people are naturally happy, but most people are dealing with some form of chronic unhappiness.
Young people today feel the same thing young people felt in 1990. They feel despair. In 1990 most everyone I knew who was under 30 was living in fear of not being able to pay their rent, buy groceries, find a high paying job, World War 3, and never being able to afford to buy their own home.
So despair is not just a human condition thing, it is also an age/stage of development thing. Things may be worse today in America than they were in 1990, but they are better than they were in 1861. It's all perspective. "I think therefore I am." The first thing necessary in changing one's exterior circumstances is to change one's interior state of mind. If you think doom and gloom you will experience doom and gloom. If you think "the best is yet to come" then you will feel a sense of optimism regardless of what home prices are today as compared to 20 years ago. Young people are just naturally gloomy and pessimistic because they can't see the big picture of life (yet). And unfortunately, many people never grow out of this doom and gloom stage of adolescence. They never grow up and instead carry it over into their "adult" existence.