My view is more that most people have a distaste for learning, education and autodidacticism because they grow up steeped in a culture that discourages these things, while simultaneously rewarding the opposite sorts of behaviors.
Caplan has a counterargument to this - twin studies and various observational studies that attempt to do similar things. He goes into detail occasionally on his blog, and also in his book:
http://www.amazon.com/gp/product/0465028616/ref=as_li_tl?ie=...
(The focus of the book is not on education, but on how variation in parenting strategy does not affect adult outcomes. )
Also, your view is not incompatible with Caplan's "elitist, Ayn Rand-ian worldview". Caplan merely asserts that at the time of entering college, it's pointless for most people. The specific reason at which it became pointless for them is irrelevant - "socioeconomic factors", genetics or whatever, it's still a waste of money.