There are books on the history of education you know. It's not like you have to guess.
But read them critically. Most such books are written by "natives" rather than by dispassionate observers. A book on "history of education" is almost certainly written by an educator who is interested in history. Such a person will tend be less critical about the value of education than an outsider.
There are similar problems in some other subfields (e.g. history of labor/unions), and of course anthropology (most people studying the Navajo tend to like Navajo culture and have "gone native" in some sense).
[edit: emphasized word Most in response to next comment]
Check out John Taylor Gatto's book The Underground History of American Education.
C.f. also http://www.cantrip.org/gatto.html
In the 1800's, a high school drop out could architect the New York Public library. Abe Lincoln became a lawyer by reading in his spare time and passing the bar exam. Today, the law requires you to have 7 years of college to practice either occupation.
Why did this happen? As far as I know it was not because buildings were falling down left and right. The most likely answer is that people who work an occupation want to erect barriers to entry, thus forcing up their own wages. The policy has a ratchet effect, as a large interest group is now created of people who are dependent on those barriers. Thus the policy is extremely difficult to roll back.
If we really want to open career doors for the most people possible at the lowest cost, we should eliminate legal schooling requirements for all occupations. Then we can return to the 19th century apprenticeship system, which was completely free and gave better career preparation.