Why is it?

Why is it that people insist on telling me what to do when they themselves have no idea what is best? I, obviously, do not know what is best either. But that is my point. I want to figure it out on my own. I want to be independent. I want to live my life the way I want. Why is it that everybody wants me to live their life? Why can't I just do what I want, how I want to?