It’s easy to be pessimistic when one doesn’t understand economics or that the innovative nature of the human mind is the ultimate resource. The incentives and price system inherent in the market process ensure that innovation will continue to improve our world. But Simon wrote that two things were certain: first, “humanity's condition will improve in just about every material way”; second, “humans will continue to sit around complaining about everything getting worse.''
-As excerpted from #5 on this list of Six Reasons We Don't Know How Good We Have It.
One of the reasons us History majors tend to be optimistic is that the historical default condition for most of humanity is to be cold (my Eurocentric background is showing), wet, hungry, and poor. It is pretty clear that economic systems matter, and the cold, wet, hungry, and poor thing is just an option these days.