Its the residual distrust of too much learning, of those clever beggars who know more than you do. As the vice-chancellor of my university said while shaking my hand as he awarded me my MSc, "I hope it was worth it".
Its not what you want to hear, and no, it wasn't...
A Doctorate is a "Floppy Hat" degree because the academic dress includes a soft Tudor bonnet, rather than the hard mortar board of a Bachelors or Masters degree.