I don't believe I can really speak for anyone else, but to me it seems like everything we are outwardly is a reflection of who we strive to become. Every conscious thought, choice and act is executed in (sub)conscious conjunction with the desire to bridge the gap between where we are and where we believe we should be. Most everyone is chasing something, and we become defined in the pursuit of it. Since the sum of our daily habits will define who we become and where we will ultimately end up, how could we ever allow ourselves to be content in mediocrity? To merely allow our lives to be governed by fate and submit to the idea that we have no control over what happens to us?
I suppose the difference in opinion will arise from one's definition of what exactly constitutes "mediocrity" -- or "success" for that matter. But in any case, I believe actively searching for the answers will help to define my own reality and allow me to know exactly who and where I was meant to be. I don't have the faintest idea what that might be, but at the very least I know for certain one day I will.