I have a different take.  We Americans have figuratively become fat and happy.  Life is good.  Standard of living is stellar compared to 50-100 years ago.  We have few real obstacles or threats.  Remove serious threats to health and happiness, the mind supplies them in the form of rather trivial irritations.  Whereas in the past the physical challenges of life, food, shelter, health, were daily struggles for almost all and united us, today, most of us slide on with everything we really need.  Still we must have problems, it is human nature.  The problems just become more esoteric.  Adversity, real adversity, is good to focus the mind and cast off superficial issues.  It is not clear that humans evolved to be as comfortable as we are today.