But is there anything rational about fearing death?
Though it may be true that only the one who lives forever never fears dying, if the ultimate of life is to enjoy it, why should we fear anything at all?
Perhaps once you reached the age of 80 there is no reason to fear death, but it is perfectly rational to fear death (or things that will cause death) when you are only 20 or 30 years old. This is because you haven't enjoyed very much of your expected lifespan.