Ultrarunning is such a niche sport. That's why it isn't an olympic sport. There aren't enough people in the sport to make finishes consistent across similar terrain. The winner of the race could be 2 hours ahead of the second place finish.
My spouse has gotten into trail running, and has done a couple of 50k's along with shorter events. This amount of variation is really noticeable. I also have a friend who rides cyclocross, and it's a similar thing. My impression as an outsider is that perhaps as a result of this level of inherent variability, the social atmosphere surrounding these sports at the amateur level is much more laid back.
