One of the biggest problem of trying to learn from history is that there are usually so many different factors involved that it is difficult if not impossible to isolate one factor and absolutely state its effects on society. Furthermore, when different people look at the same event, they often see it very differently depending on their own viewpoint.
For instance, although historians generally seem to regard the GI Bill of 1944 as one of the most successful and influential programs of the 20th century, libertarian economist Thomas J. DiLorenzo argues that "In truth, the G.I. Bill was a budget-busting middle-class entitlement scheme that had destructive effects on higher education, and set the stage for virtually all our current educational problems." According to DiLorenzo one of its most harmful effects was that "It served as a model for how politicians can grow the government without provoking public revolt, and caused an entire generation to regard government as a benefactor" and "It made the centralization of education possible for the first time in American history. That in turn opened the door to the ruinous politicization of higher education that has marked the past half century."
A Department of Defense article takes a rather different view of the bill:
Passing the GI Bill brought more than 16 million veterans into a peacetime economy. Since it provided education and home ownership opportunities to millions, some dubbed the bill the "Magic Carpet to the Middle Class." Historians say the GI Bill contributed more than any other program in history to the welfare of veterans and their families and to the growth of the nation's economy. The bill is credited with preventing a post-war relapse into the pre- war Depression.
It seems to me that the key phrase here is "magic carpet to the middle class" because universal access to higher education allowed those who previously been unable to escape the bonds of poverty to find a new path to wealth.
The liberal Heartland Institute is even more generous in their praise of the GI Bill:
Whereas college in pre-war days had been regarded as just for "teachers' kids or preachers' kids," the G.I. Bill opened higher education to all--including those who previously had been discriminated against. Quotas restricting admission of Jews and Catholics disappeared as schools were swamped with veterans. Previously all-white colleges admitted African-Americans. In fact, one-third of veterans at college between 1946 and 1950 were black; many went on to become leaders in the civil rights movement.
"The pursuit of higher education became considered normal for everyone, whether they were white or black; Jewish, Catholic, or Protestant; male or female," notes Stephanie Swanson in a recent study of the effects of the G.I. Bill in The Concord Review.
Swanson points out the G.I. Bill also was instrumental in expanding the middle class in America beyond its previous predominance by white Protestants, making it accessible to people of other racial, ethnic, and religious backgrounds. As the number of blue-collar workers decreased by 4 million after WWII, the number of white-collar workers increased by 10 million. The result of the G.I. Bill was "the American Dream come true," said political historian Milton Greenburg.
While I haven't been able to find an entirely convincing estimate of costs and benefits, one article offers the following breakdown:
From 1944 for the next 30 or so years, about 70 billion dollars was spent on the GI bill. And what people have estimated is that, because of the income potential that people gained as a result of this training and education, that they have paid taxes 8 times 70 billion dollars. So well over 500 billion dollars in taxes paid on this 70 billion dollar investment, so that its paid of(sic) handsomely.
Many, myself included, would argue that it was the GI Bill and the influx of college-educated workers into our economic system that led to the technological leap forward for the United States in the second half of the 20th Century.