"Why do we think that way when we're young, that we're immune to damage? What changes?" I see you've received a lot of answers already, but not an explanation

"Why do we think that way when we're young, that we're immune to damage? What changes?" I see you've received a lot of answers already, but not an explanation (worthy by my standards). Here's my stab on it: 1. Remember how everyone got to ride a bike in the first place. It looked dangerous, yet we had to get over our fear AND try to suppress it consistently long after the point of riding and not falling any more. And that kind of fear suppression exercise was necessary again and again all over our childhood. It's no wonder that with so much repetition it grew to become part of our character, at least for a while, at least until the voices that once encouraged us to overcome our fears went silent. 2. The level of responsibility we bear and the awareness of it, including the responsibility for ourselves, especially enough to feel it in our choices, grows only with time. As younglings, we care less about "serious and boring" (i.e. "act responsible") and more about "fun and exciting" and weight our decisions accordingly.