As with anything else, I think this is a complex issue with many facets. First, I wouldn't discount the void left behind by spirituality. Most people are not very spiritual any more, even if they believe in a higher power. I had a mentor for years who passed away from pancreatic cancer. He was brilliant but tortured. Common story, no? He finally found peace when he began to study all of the world's religions. He chose to call them wisdom traditions. He was raised Jewish but studied everything. He began to see the common threads or the true nuggets of wisdom. Those are what got him through and to the other side. Those are what brought him peace. He was not a scientist but I am and when he began to share those nuggets with me, I could see the possibilities of how they also could be consistent with science. The problem is, when you are no longer immersed in that environment or no longer have people you regularly talk to about these things, they can fade into the background of your mind. Then you start living in the past or the future again. You lose self awareness and lose focus on the present. And when you live in the past or the future you are so much more likely to suffer. It is unlikely that any of us are bio-chemically perfect and/or that we have been fortunate enough to have not had a psychologically traumatic event in our lives. Those things often lead to attachment of some form. And then you either fear losing that which you are attached to or become depressed over something you already lost. It becomes brutal when those attachments are people. Loss can take on many forms with people. It can be the worst form in terms of death or can simply be separation. Now, if you are brilliant, you also probably think, A LOT. If those thoughts are in the past or the future, you torture yourself, A LOT. Then you become mentally exhausted. Eventually, you reach a breaking point and death seems like the best path to peace. That is all people really want, deep down. Peace.
There also seems to be a connection with anti-depressants. It seems they often make matters worse. It depends on the person. We have a long way to go here, as several have mentioned.
And I will add that our society evolves and not always in a direction consistent with achieving inner-peace. I think America has long been between a rock and a hard place. We look at the lifestyle that those who live on the Mediterranean live and we want that for ourselves. Who wouldn't want a low stress, laid back, lifestyle??? But their economies struggle because they don't, in general, "work hard enough". Then we look toward Asia and see threats to our own economy because, relative to them, we don't "work hard enough". Hard work and enjoying the fruits of our labor is in the DNA of Americans so we are self-programmed to want to compete with the Asians. We don't want to be "out-worked" by anyone. In a way, our society itself is bi-polar. It is easy to always be doubting yourself and your choices when you want two opposing things at the same time. You constantly feel torn. Now, consider that over the last 20-30 years, the percentage of the American population that is Asian-American has been growing rapidly. Initially, they came here as international students. Some undergrad, some grad. Many of them brought with them that fierce competitiveness of their culture. Why their culture is that way is another question for another day but I believe much of it has been driven by decades of scarcity. Next, consider that most of these immigrants were the very top of their country in terms of socio-economics and intellect. I am talking the top fraction of a percent. Maybe hundredths of a percent. So, in terms of profession and education, they end up mingling with the best of the best of our country. Again, these are the people that think, A LOT. They fear not being competitive so they raise their efforts. They sacrifice more of the little things to better compete for the big things. But those little things provide the variety that is the spice of life. Has anyone looked at the insanity that is the spelling bee lately? Think what you want but two of the recent winners actually went to grammar school with my kids. I can tell you that these kids sacrifice A LOT of their childhood to bring status and recognition to their families. Kids that age don't naturally get geeked up about spelling, no matter how nerdy they are. This is coming from their hyper-competitive parents. Then the mentality leaks into high school. Have you seen the courses some of these high schools offer now?!?!?! There are kids that have taken Vector Calculus, Linear Algebra and Differential Equations by the end of their junior year. This push for more and more and more comes from that hyper-competitive mentality. If one kid takes Calc 2 then I want my kid to take Vector Calculus so he has a better chance to get into Harvard. Then it becomes Linear Algebra. Then Differential Equations. More and more and more. But at what cost? These kids barely sleep and barely have down time for those little things. And it is no less insane with extracurriculars and community service. Kids are pushed to play more and more sports. They are pushed to be better and better by playing and/or going to camps in the summer. And community service? Now it has to be hundreds of hours and often away from home in third world countries because the key is to be "distinguished" in some way. And if it isn't community service, these kids are pushed to do "research" over the summer and often away from home. It is common now for kids to skip lunch to take an extra AP class so they can have a higher class rank. Could we do any more to raise exhausted and stressed out kids?!?!? Is it really any surprise that the number of kids in therapy at top colleges is rising rapidly? How could it not! Cornell had to put nets under their foot bridges because kids jumping became an issue. I know of at least two kids there that were told they were a disappointment because they only got into Cornell. Think about all of this for a second.
So we have a push to want more because we don't want to be seen as lazy or less. On top of that we are losing our spiritual compass and that is leading to attachment and living in anything but the present. Simpler times were called that for a reason. The less simple life becomes, the more people that get pushed to the breaking point.