How come so many people seem to not know what to do / how to be an adult? What makes you feel like you’re still a kid?

I’ve seen it here on reddit so many times. “I don’t know what I’m doing”, “I don’t feel like an adult, I have no idea how to ‘adult’ ” etc.

I think I’m misunderstanding something because I don’t get it. I feel like I have control in my life. What to do, what I need to know, and who to consult or where to get information if I don’t.

Can somebody give me examples on what makes you feel like you’re still a kid or don’t know what you’re doing in life?