Fear, in some situations, can save us. It’s a natural instinct - ever heard of the phrase flight or fight. “Flight” is the running away. You can physically run, but also mentally run away from a problem.
To some this may be the only way they can cope with things and situations but it doesn’t lead to a final resolve -closure- so you’ll find yourself running away from things more often then facing them and fixing the problem. This is where is may be destructive and harmful behavior.
In a life or death situation, whether your own life or another is in danger, it may not be safe to mentally check out, in fear that it might leave you mentally unaware of your surroundings and miss instruction from authority. It also might not be safe to physically leave as well because maybe the danger is,for example, a weather disaster - in that case you don’t want to run around.
Hope this helps!