Right this is sort of the point. You were not aware, if you had based your defense against unlatched vulnerabilities based on your knowledge 24 hours ago, you could quite easily have gotten pwned. Knowing about all vulnerabilities that could affect you and how they work is incredibly difficult. I don't want that risk (nevermind that even if I was ok with that risk, my company would throw a fit if they found out I was using an unpatched OS).