Pencil sharpeners keep pencils usable. Knife sharpeners give knives longer lives. Some minds are incapable of being "sharpened". WHY?

Doofylucy is one of them. He is always the same. No desire to learn anything. No desire to get better at anything. No desire to learn or read or listen or think. He is perfect in his below-averageness. Izn't he?