Religion

you can still feel, think, smell...nonexistence is a hard thing to imagine. And it is legitimately scary. It's almost the entire reason w hy religion was created to deal with the scariness of nonexistence. Pain and worries are preferable, and life is a mixture of that and joy and happiness and laughter (unfortunately some get a crap balance of those things but almost everyone gets some of all of it).

I don't think there's an afterlife either, but the whole "grow up" mindset over it is ridiculous. It's not an immaturity thing, it's a quite natural reaction to one's own personal extinction.