Here's how I think people like CKT grow up:
They're born as a baby and get lots and lots of care from their parents, siblings, friends, etc, like they should. Though the parents think the baby is loving helpless as it grows up, so they continue their care as they did when he was first born until they're like seventeen, like CKT claims he is. As the process happens, the parents always say things like "You're the best!" or "You'll be the king of the world some day!" The child assumes this is true all their life, until they're, like I said, seventeen. At that point, they're an egotistical stuff like CKT.