average hourly earnings have not increased in 50 years

Over the past 30 years, a larger and larger portion of America's income growth has gone to those in the top 10% of incomes, and especially those in the top 1%. This is a major change from the prior 60 years, in which the top 10% and the bottom 90% shared in the income gains.
A stark and startling example of this trend is the fact that, adjusted for inflation, "average hourly earnings" in this country have not increased in 50 years.

end quote from:
The Middle Class Is Broke: Pew Study Reveals Real Problem With Economy

So then, why is this true? 

One way to look at this is that overpopulation worldwide itself has caused this problem because when there are more people there is less for everyone. So, even if no one planned this this same outcome would naturally result from overpopulation.

So, it is a definite truth that overpopulation, global warming and global climate change, and just fear of all classes of people has created this outcome. So, what this results in usually is only the most aggressive and innovative people in all classes survive. Unfortunately  this is the end result always. And everyone else dies young or slowly starves to death. So, with an education more innovative ways of saving lives and educating and feeding and clothing and sheltering people will be found. However, it is important to note that there is always an upper limit to how many people can survive in any given area of earth or even on earth itself. So, no matter how benevolent people tend to be there is always an upper limit and that limit depends upon how much food can be grown worldwide in any given era and then shipped to whoever needs it. It also depends upon clean non-polluted water for people to be able to survive.