Sometimes at races, things can get a little hectic in your heat. Crashes happen- it's a part of the sport. There is a huge variable of things that could take you out at any time, causing you to get eliminated. It could be other riders, random wildlife on the track ala Buffalo Bill or Whistler, or just self-confidence.
Sometimes you avoid disaster.
You need to be prepared for things to get gnarly, and when they do- and they always do eventually- you should have some sort of strategy to get through these situations as safely as possible.