The determinants of happiness are remarkably similar around the world, in countries as different as Afghanistan, the U.S, and Chile. Income matters to happiness but only so much; friends, freedom, and employment are good for happiness, while crime, poor health, and divorce are bad.
Paradoxically, people in places like Afghanistan can be as happy as those in much wealthier and safer ones like Chile.
One explanation is the remarkable human capacity to adapt to adversity and hardship.
While adaptation may be a good thing, it can also result in a collective tolerance which is difficult for societies to escape from.