The model of education as signaling for the labor marketing has been thoroughly developed by Bryan Caplan; for some examples, see here, here, and here. I think the argument is pretty convincing, but it leaves a few details unexplained. Namely, some majors - especially liberal arts - are not even very good as signals!
The highest unemployment rates for college graduates are found among architecture, art, and humanities majors. Especially given the relatively low salaries for jobs in these "industries" why go into serious debt to get a degree, when the signal is likely to be weak or even totally ineffective? While the number of liberal arts colleges has been declining over the last 20 years and business is the most popular major for under-graduates (chosen by 20% of students) the liberal arts curriculum is far from disappearing.
It could be that these students are maximizing with regard to something other than wealth, such as social status. This may accrue to either the college student or that student's parents, who get to brag about how their son/daughter will be a progressive hero and "save the world one day." Parents have incomplete control over what major their child picks, but at least some power to encourage or discourage certain fields of study.
Thinking of education as a status symbol helps to explain variation in choice of majors across countries. In the United States, the poor and middle-class can get luxury items like fancy cars, jewelry, nice TVs, smartphones etc. by using credit (Robert Kiyosaki's "Rich Dad Poor Dad" observes that this is a big reason why they do not ascend to the capitalist upper-class). Seeing someone with nice jewelry or the latest tech is no longer a good indicator of high status in America; in fact, it is often a signal of the opposite! A liberal arts degree then becomes a new status symbol, a way of displaying "yes I can spend four years doing nothing productive, and rack up debts while doing it, because money isn't important to me."
In China, by comparison, most of the affluent or middle-class people have attained that status within the last one or two generations. The rich in China display their wealth through luxury items, but parents still often discourage or frown upon liberal arts degrees (or so I'm told by someone with personal experience). Based on the social signaling theory sketched out above, one would expect that as the middle-class in China grows and expensive items are no longer limited to the nouveau riche, more will go get liberal arts degrees, instead of the focus on STEM (science, technology, engineering, and math) which is the stereotypical image of Chinese students currently.
If this model is accurate, it just further reinforces Dr. Caplan's point that we should not be subsidizing higher education as much as we are now.