Two Obstructions to Learning

The same recognition arises whenever I watch a beginner learn something I'm good at, or whenever I myself try to learn something new:

It's not as difficult as you think....and it requires a great deal more concentration than you were expecting to apply.

Always, those same two contradictory missteps in bizarre tandem: fraught insecurity and blithe overconfidence.

Why do kids learn so much faster/better/easier than adults? They learn via play (i.e. the application of concentration for pure pleasure).