Just because we are biologically tuned to "market" ourselves, for leverage in survival/gene-spreading, I don't think it's correct to state that the "entire purpose" of life is to market oneself. Nor does it make sense to say all actions are rooted in this need. In-fact, it seems _most_ actions are in service of other basic or secondary needs. Where is the marketability in taking a piss? Or reading a novel? Or taking the dog for a walk?