I should make it clear, I recognize I am sort of a poster boy for when education would make sense, in terms of being extra smart and in terms of the kinds of jobs I like to do. But your assertion of signalling value only "forgot" about STEM, MBAs, and people who want to be professors, and doesn't address the market failures of such seemingly efficient businesses as Bell Labs, Caltech, and Qualcomm in finding value in the educations of the educated and not just in their educability.