It can indeed seem dumb to you or me, but if their only purpose in 4 hours plus has been to try to win the stage, and there is a slight possibility of it, and you see that others are trying to do the same thing, and you are full of adrenaline (let's assume just that) and short of oxygen, and your career is predicated upon getting to a line as quickly as possible, and you don't know they won't decide the winner that way, and you are young and competitive, and your heart is at about 190 bpm, and ...
Plenty of people do much dumber things in those circumstances.