What makes physical death so special that you do want to exist before it happens, but don't want to after? Why not pick some other arbitrary event, like say, the next New Years?

Living _forever_ seems like... not necessarily that attractive an idea.

(Also most of the afterlives on offer don't seem particularly attractive.)

As someone who doesn't believe and never has believed that there was an afterlife, there is something kind of horrifying about the _inescapable, eternal_ nature of such a thing. I think this may be different if it's a concept that you've been sold on as a kid, but from the outside, it's really kind of unsettling.

The fact that somebody doesn't want afterlife doesn't imply that death is a special moment for them that separates wanting to exist from not wanting.

They could have "picked" another moment. It might be next New Year or a moment in the past or even a moment before they were born. The moment of death is simply the "earliest convenience" to end unwanted existence.

for me it's the fact that I could theoretically end it (modulo quantum immortality, my worst nightmare). the afterlife is usually sold with "guaranteed forever". I've been in so many situations that you might think "oh I wish this could go on forever" and then regretted it, that I want to make sure there's a way to pull the plug.

Spending the rest of eternity with other human beings is not very appealin.

What if you could spend it with cats? What if it didn't have to be forever - if you could end it any time you chose, like after 1000 years or whenever? It seems what you don't want is only a very specific version of an afterlife.

Does any major belief system actually have an afterlife in which you can _die again_?

I suppose various types of reincarnations might be that. Or afterlife is just temporary state in between. I suppose reincarnating just to die again is something in some belief systems. Sometimes with goal of being liberated from the cycle.

Some people enjoy playing games in 'Hardcore' mode (see e.g. Subnautica) where if you die, instead of respawning, the game ends and your save file is deleted.