Because successfully keeping your feet under you when sliding down a mountain depends on commitment. Either you're skiing, or you're setting yourself up for a fall. Think of the famous Star Wars quote, by Yoda, "There is no 'try'; there is only do." Of course you shouldn't overstep your skill, but if you're thinking about falling, then you're not thinking about skiing. You could expand this - together with other answers - into a hub, y'know.