In a good article questioning the human drive for more power, emphasis mine:
Even if you don't buy into this picture of Pleistocene richness replaced by modern poverty, it is clear that the immense rise in human power has not been matched by an equal rise in human happiness. We are a thousand times more powerful than our hunter-gatherer ancestors, but not even the most optimistic Whig can believe that we are a thousand times happier. If we told our great-great-grandmother how we live, with vaccinations and painkillers and running water and stuffed refrigerators, she would likely have clasped her hands in astonishment and said: "You are living in paradise! You probably wake up every morning with a song in your heart, and pass your days walking on sunshine, full of gratitude and loving-kindness for all." Well, we don't. Compared to what most people in history dreamed about, we may be living in paradise. But for some reason, we don't feel that we are.
One explanation has been provided by social scientists, who have recently rediscovered an ancient wisdom: our happiness depends less on objective conditions and more on our own expectations. Expectations, however, tend to adapt to conditions. When things improve, expectations rise, and consequently even dramatic improvements in conditions might leave us as dissatisfied as before. In their pursuit of happiness, people are stuck on the proverbial "hedonic treadmill", running faster and faster but getting nowhere.