Existential angst and worrying a ton about your obligation to society and so forth almost always turns out to be a projection of your worries about yourself onto society at large. You're not really worried about some abstract duty or obligation, instead you have a low opinion of your own competency/worthiness and are worried that other people will come to share that view if you're not able to measure up to some abstract standard,
Sometimes our minds suddenly "click" and we see a topic in a new light. Or sometimes we think we understand an idea, think it's stupid and ignore attempts to explain it ("yeah, I already know that"), until we suddenly realize that our understanding was wrong.
This kind of insight is supposedly hard to transmit, but it might be worth a try!
So, what kind of important and valuable insights do you wish you had earlier? Could you try to explain briefly what led to the insight, in a way that might help others get it?