Why not? It's fear of the unknown coupled with a more-or-less unpleasant transition.
Then there's the fact that most of us have things we still want to do and won't be able to do them if we fall off the twig.
why human beings afraid to die?
Generally, fear of the great unknown, fear of oblivion, fear of hell. But not all people are afraid to die. Some are strong in belief, we call them faithful; some have accepted the inevitable, we call them realists; some can't wait, and want to take others with them, we call these people lunatics.
I'm not afraid to die. I have issues with how bad it's going to hurt.
Dear Anon,
This answer does not directly address your question, but some say fear of death is our most basic fear, underwriting everything else...
The story goes that 2500 years ago in India there was a great king who raised his son in a beautiful walled palace so he would never have to face any problems of life. Well the prince married, had a child, but finally got curious and made three forays outside.
* * *
He encountered sickness, old age, and the third time saw a funeral... well after seeing death he left the palace for good. The prince's name was Siddhartha, and he became the Buddha.
Everything has this psychological want to live, it's a fear of leaving behind your family and friends I suppose. Suicide attempt survivors will tell you that once they did the deed they instantly regretted it.
whats next??
pain??
Fear of the unknown. Fear of leaving everything that is familiar and loved.
Missing those you leave behind and the time you spend with them. The idea of no longer existing. You cannot escape it, it will happen, sometimes the scariest thing is how it will happen.
People are afraid of being forgotten.
It is the unknown for some, and for others it is an end to their personal journey, and a replenishment back to mother earth. Some spend a life time in the service to a concept rather then truly livng life like this is all there is . . . If they enjoyed the servitude to their fantasy then whats the harm.
Because I'm sure I'll be forgotten quickly!
Thanatophobia is fear of death.
Here's a site that is worth some reading: