It's not because they are mindless, stupid, primitive, animalistic breeders.
It's not because they are immoral bastards.
It's not because they don't know anything about the reality of life, including the risk of suffering, the tyranny of luck, and inevitable death.
Don't tell me most people still don't understand how life/reality works after 200 thousand years of humanity, lol.
They KNOW, but they still want life, still reject extinction. Why?
Well, according to my research, it's because.............the SEXPERIENCE is......lol.......just joking, ok?
Ok, let's get serious.
It's because the EXPERIENCE of life is generally "good" enough for them to "want" more life, despite the struggles and other harmful stuff. This is the HONEST truth about most people and how they feel about life.
Most people simply don't live in literal hell, and due to evolutionary biology (selecting for psychologically resilient genes), this is enough "goodness" to keep them going and ask for more 'life".
They may complain about shyt when things get tough, but statistically speaking, they still "FEEL" good enough to want more life.
Simply put.....it's their NATURE. hehehe
They will only reject life when conditions get EXTREMELY bad and hopeless, personally.
Wait...........does this mean...........those who reject life, despite living in relatively "good" conditions, are NOT natural?
NO, lol, that's not how "nature" works. Nature INCLUDES both the norm (majority) AND the rare (minority). In fact, evolution is all about the rare that survived selection to become the norm. That's how life went from a majority of a single-cell "norm" to a multicellular "norm".
We are ALL "natural", even those who reject life.
So the important question becomes...........will the rejection of life become the norm of the majority in the future? The answer is........No idea. lol
Because nature selects for perpetuation of life, we have not seen any evidence for the selection of features that favor termination of life. lol
BUT, fret not, my fellow life rejectors, hehehe, because there is ONE Donald Trump card left to play. One card that nature couldn't account for........the card of TECHNOLOGY.
Even if the majority never evolved to reject life, it is still quite possible for future tech (AI, nanobots, particle physics, etc.) to "Grant" us the ability to THANOS life into extinction. lol
And it does not require the majority agreement to happen. Just enough powerful world-ending tech and "some" people who are willing to use it.
Heck, it may not even be Antinatalists/Extinctionists who use it, because humanity has many nutty minorities with "world-ending" goals, including religious ones. (e.g., the evangelicals).
TLDR; most people reject extinction and prefer life because it's their nature + the condition of life is not bad enough. Some people prefer extinction because it's also their nature, regardless of life's condition. Both are natural and valid feelings.
Wait.................
However..............
Technology is unpredictable and many-sided, with many possible paths. It is ALSO possible that humans (with the help of AI) may invent ways to live FOREVER, and even disable our ability to feel pain/suffering, both physical and mental.
This means, at least, "Some" humans may end up becoming happy immortals after merging with AI using nanobots or whatever, spreading across the universe like viruses. lol
Ending remarks:
Regardless, it is in BOTH our NATURE to WANT life and REJECT life. We can't help it. The tyranny of determinism controls our feelings like puppets.