In the middle ages, if you wanted to do scientific research, you had to pay yourself the career, meaning no salary, just living on your savings, which meant only the wealthiest could afford to dedicate their life to scientific research.
That's why there were so few inventions and discoveries.
In the renaissance, people become aware that there was 1,000 years of dark ages, and that science had been forgotten. They studied old classics and were able to re-create science. It was continued refinement of ideas by carefully testing them. But only the wealthier could afford.
At the same time the ideas of the illustration were born. Men should be free. Ideas should be free. People should be free to express their ideas. Science advanced so much in 200 years that vapor machines were invented. Then the american revolution happened. Ten years later the French revolution happened.
It was thought at the time that democracies could not exist, because Plato wrote in "Res Publicae - The Republic" that democracies would convert into demagogic governments, which meant that governments would invent enemies in order to keep in power and destroy democracy. Because of that several european countries wanted to re-conquer the americas. Americans decided to:
- Educate their people for free.
- Have everyone have guns.
The result is that the USA has more than 200 years, but the education system is failing. The main reason is that sometime in the past it was decided to follow the "no child left behind" policy, which meant no selection in the public system, so the students are mingled, good and bad, and of course the good have no incentive to study, since the tests are dumbed down for the stupid.
Do we need more PhDs?
If that were the case, then PhDs would make a lot of money, at least following the economic theory. The only problem is that it is very hard to make money on science, and even if you do, it takes several decades of research, so it is a very expensive and very risky investment. No rational investor would invest in science. Only if the result of the research is already proven and you just need to produce the thing, sure, some investor would be interested. We can't call that science though.
So I guess the answer is no. If you pursue a PhD is not for the money, but because you are interested in learning more about a subject. If you study computer science, maybe you go work for Google, Yahoo, Netflix, Facebook, Twitter and the like, and recover your investment of time and money, but otherwise it is a rather risky investment.