Being grown up isn't one end goal in life. Growing up can happen continuously throughout a person's life and should continue through a person's life. With that being said, I don't plan on becoming a grown up. I plan to continue to grow up until the day I stop breathing. Humans are built to learn and adapt to their environments. Since the world is ever changing and developing it makes sense then that humans will also develop and grow continuously.
If I stopped learning once I "grew up" I would miss out on so many different things in life. I don't believe a person can ever know everything about their field of expertise or work. If they do know everything that is known about something they should be the ones driving the movement forward. Too many people are content with hitting a certain point in life and simply coasting through the rest of adulthood. I hope to be challenged through life so that I don't simply coast through.
The world would be so boring if we all grew up. I don't mean I'm going to be immature and refuse to take responsibility throughout my life. I just don't want to be so serious I miss out on enjoying my life. I work with children and they still get excited over all the little things in life. Adults lose so much of the excitability they once had.
I hope to continue to learn, grow and get excited over the little things in life.