/lit/ - Literature

What do people mean when they tell you to grow up? I feel like the final result of the notion to 'grow up' (not in the biological sense) is just straight up narcissism. You love yourself so much that you don't give a fuck about anything or anyone, do your thing regardless of questioning it and stop being distracted by emotions. It's similar for parents who extend this narcissism to their child (maybe rightfully so) to a degree where they'd kill for the child. Depression and doubt is not a possibility for a 'grown up'. This is the best esplanation I can come up with when trying to understand why older people are like they are now where I am getting older myself. How else can you even bear to live in this world? Narcissism is the only cope that works long term.

Also, any book recommendations on this?
Pic related is just a random qute from google search which illustrates to me how stupid and empty this concept is.