Knowing yourself has extraordinary prestige in our culture. It has been framed as quite literally the meaning of life. Self-knowledge is important for one central reason: because it offers us a route to greater happiness and fulfilment.
A lack of self-knowledge leaves you open to accident and mistaken ambitions. Armed with the right sort of self-knowledge, we have a greater chance of avoiding errors in our dealings with others and in the formulation of our life choices.