A hypothesis could be that these great developers became what they are due to an extreme internal drive at a young age; they already have tons of experience and the right attitudes/thinking patterns when joining the work force. If they continue learning (and why shouldn’t they, given their internal drive), how can anyone compete with them?

This intrinsic motivation implies that companies really can’t “grow” great developers, nor “pick them before they’ve blossomed”; what they can do is step aside and not create obstacles.