I have this theory in life, and I think it applies to most of us

We as people develop feelings for many things, people, items, animals, activities, etc... The possibilities are endless. And as we go on in life, we become tempestuous about these things and we feel like the world is going to end when we lose those things.

So, my theory is that we are not afraid of dying because it's something we have not experienced before, nor is it because of the pain of dying, but because of losing the things that we became sentimental to.

-Heruchi