I have come across this from Paul Graham before, but I think he is saying something very important about learning in general. He points out that there are lots of skiing instructors, but not many running instructors. When you learn to ski, often your intuition is to lean back. Big mistake. Often you need to lean forward. It takes a while to re program the intuition.
I used to think most medical students knew how to learn and acquire expertise efficiently. I no longer think this way. In particular, there is an over emphasis on rule based strategies, rather than naturalistic ones. Just as people over emphasise predicate calculus in thinking about the world, so we and they, are often prisoners of mistaken theories about how ‘learning works’. Much learning is very unnatural.