>So why do so many people who have chosen to take that extra step, just stop educating themselves when they graduate? Because most people don't go to college to "get an education." They just go there as a hoop-jumping prerequisite to hopefully get "a job" and with that, a middle-class lifestyle. It's not that they want to know Shakespeare (running towards an academic milestone), but rather, they simply want to avoid…
I'll restrict this comment to education for the aristocracy rather than religious functionaries. Its traditional function is well-understood, and bears little relationship to what you might think of as "education", the development of knowledge, today. The purpose of elite education is to acculturate the elite into a harmonious social group, with shared values and a shared cultural background -- such that, when two elites meet for the first time, they can interact comfortably and don't come across as off-putting to one another. So you have things like classics education; it doesn't really matter which texts are "classics", and their content is of no use in itself -- but as long as everyone has read the same "classic" works, they'll get each other's references and feel that they're all part of the same group.