"He who knows most, knows best how little he knows."  —Thomas Jefferson

An observation that people report a much higher level of skill and understanding in a subject early on in their learning about it, than they actually possess.

Could be (?) thought of as the first stage of learning about a new subject is grasping the essence, while the next stage (or stages) is about learning what we don't know about the subject. On the other hand, it could be that this is just a very ironic speculation. :-)