Non-existence may be preferable to existence

 Non-existence may be preferable to existence (as when really tired, sleep is preferred).  

The law of diminishing returns requires time to dissipate.

Human minds (egos) that revel in power, wealth, and glory or other great accomplishments tend to want to live forever, to have “eternal” or everlasting life.

Buddhist “in the know,” tend towards self-annihilation or non-existence, meaning no more reincarnation (as they understand the word).  Liberation from multiple lives is a Buddhist quest.

Death of a human body, and death or termination of the awareness, intelligence, energy, consciousness, observer, watcher, or “spirit” or “soul” (whichever you prefer) is only considered dreadful and unspeakable by some human egos.

Absolute liberation from existing (never again being conscious, never again waking from a night of sleep, liberates a human from living a life, or lives, it never asked for, but rather, was “forced” to live.