This I can say for sure, though my experience only lasted three days.
My friends ran. I ran because my friends ran. I remember trying to keep up with them and I will say that was the hardest thing I've ever tried. I watched their derrières disappear over hill after hill and at the end of it all I was still the one who was gasping for air and puking.
My running joke is I played football because I didn't like to puke from running cross country. Editor's note, I was 125 pounds, I wasn't that hot at football either.) I lasted through track season, but after three days of running my own derrière off I walked up to the coach and said "Coach, I hate throwing up, I'm just not cut out for this." He insisted it would get better but I didn't believe him in my fog of runner's high.
So when I see these kids, many of whom are brilliant scholars capable of doing math equations in their head that I can't even cypher with pencil and five erasers, lying on the ground gasping in pain, I am in awe. This is the hardest sport I know.... well I'm a terrible swimmer so maybe that is harder still?"
it was the only I time I ever quit anything. Running is hard. These kids deserve our respect.
And it gets crowded around the finish line because often that spot where the clock records their final time, they are just plain done.