As to the case of someone like Einstein, Newton, etc--we have to keep in mind that we don't have the ability to necessarily recognize and nurture extreme talent in young people at all times and places in history. We know about these cases like Terence Tao because his parents were successful in getting him where he needed to be at a young age, but that doesn't mean there aren't other Tao-like kids out there who are just not having that educational experience. They may yet grow up to do amazing things.