You can wonder and savor all the magic of the world and be late for a late meeting. You can be a child beyond being the son or daughter of your parents.
And this quote has another, more magical meaning. Even you had the gloomiest childhood, you can kinda go back in time and sprinkle pixie dust on it. Elon Musk hasn't set out to create time machines in mass production, I know. But there is a way to actually do the magic, you won't need a thousand dollar gadget for that, you won't need to spend years in the Himalaya at the knees of an enlightened guru. All you need is the everyday pixie dust you already have: your imagination and your ability to tell stories.
I don't know if someone actually conducted this experiment, but you use your imagination, it's a thought experiment. Suppose you have a vivid memory of your grandma giving you a cute plush bunny for your birthday when you were five. You remember the touch of the bunny, its long pink ears, your granny's smiling face. Now you start telling a different story of a bunny with funny short green ears you received from your dad for your fifth birthday. You keep repeating this story, you tell it to your friends. When you hear someone mention a bunny, you tell them, "hey, that reminds me of the bunny that ..." When your partner shows you a lovely set of green dishes in the shopping window, you can recall how this green recalls the color of that bunny. You get the point.
A few months pass and you are back to the research lab. They ask you about those childhood moments of yours when you received the bunny. You may have an uneasy feeling it's not a real memory, but you can't help remembering your father giving you a bunny with green ears. Yes, you can even remember his smiling face, the hug he gave you. If this is a long-running experiment and they call you back after a couple of years, you'll have a changed memory and no real doubts about it.
Now do the same with the whole gloomy childhood. Take a really depressing scene, sprinkle it with pixie dust, give it a twist, and keep telling the twisted version. Then take the next scene. You get the point.
We tend to think of the past and of our memories as static and objective truths of life. They are not. They are subject to change. So it's never too late to have a happy childhood.