Knowledge and Sophistication
Childhood and adolescence are many things; sophisticated is not one of them.
I spent much of my childhood and teen years feeling ignorant; understanding at a fundamental level that there was much I didn't know, that was too complicated, that "adults" dealt with and which was often completely confusing when approached without knowing how to approach it.
Childhood can be a happy time, but it is happiness born (to a greater or lesser extent) of ignorance, and its pleasures are (consequently) many but shallow.
Children do not understand art. Children do not understand sacrifice. Children do not understand love -- not really. They don't understand just how complicated, confusing, and entangled human relations can be. They don't know how indifferent the world is; they don't understand higher truths such as evolution (an in-depth understanding) or the rift between the spiritual and the material within ourselves, which is so important to so many adults.
No child reads and truly understands Henry James or Nabokov; these are adult pleasures, which I would not trade for the anything -- not for anything. Certainly not the illusions of my youth, which were many.
Yes, adult life is messy, complicated, cruel, mean, confusing...
the lows are so low, that some take their own lives.
the highs, though -- they are infinitely greater than anything a child is capable of.
Adulthood is not for the faint of heart. It's not safe. But yes. It's fun being an adult -- much better than when I was a child (< 20 years old).