But will he not in most cases remain at fairly low wages and have limited opportunities for all his life in comparison to someone who got a B.A. in a useful field?

I believe that this is a platitude that has become a stumbling block.

The problem has become; if one borrows enough money, or is handed enough by his parents he can.get a degree in a "useful" field. The problem with this is it does not sort out people by how likely the are to succeed.

In Gladwell's Outliers, he covers this well. Intelligence and training do not guarantee success. It takes other factors. In one chapter Gladwell describes a divergnece test. It is a backwards test. Instead of asking for a solution to a problem, you are given a solution and asked to solve as many problems as you can with it.

(No I will not type it out for you, buy the book.)

One of the rolls of college used to be the winnowing process. Those that could not adapt, and answer the struggles that were presented washed out. Today, between support from parents and government many are pushed through school.

On the other hand, a degree can be the entry to some jobs that no amount of skill can get you. I was working as a Technical Security Specialist for an intelligence agency. I have a military background in electronics and telecommunications. I was looking for compromising emanations. I saw a job a security generalist. It was a cool job. It was field work, and was more like what you might see on TV.

I had the skills, but I did not have a degree. From the position that I was already in, inside the organization, inside the department, I could have gotten the job with a liberal arts degree. I still do not have the degree and I am still a technician. (I am not complaining, when I walked home today the yard was mowed and the house was clean...nice..real nice)

The problem with a degree is the expense does not seem to increase maturity nor does increase income a great deal. The best thing it does is get children out of the nest. However, a stint in the military will do the same and it provides funds higher education later.

Cheers
Qazulight