That it owes you stuff for free. Entitlement is a huuuuuge problem.
Probably that it will turn out as they planned when they were young. Life is so interesting, with many unexpected dips and turns! Enjoy the adventure!
That many of the same views and opinions they have is also shared by the majority.
That you have to please other people.
The biggest misconception that people have is that they can live their lives independent of their creator and be successful. The other is that our creator is uncaring, disinterested, unloving and not capable of giving the direction that works for us to live by.
That you can be happy without God in your life,there will always be something missing no matter how rich or famous or educated a person may be. Psalms 144:15 and Matthew 5:3 reads,"Happy are those conscious of their spiritual need, since the Kingdom of the heavens belongs to them."
Individuals sincerely believe that they are the protagonist of this world, when in reality they are an inconsequentially flat character in most people's story.
That it doesn't last forever.
Nothing ever dies. It just transforms.
Remember to remember.