In my case I've never wished for something so futile and undesirable as existence, having the ability to exist is such a dreadful, pointless burden that causes nothing but meaningless suffering. My wish to die is a result of becoming aware, it's a result of having awareness of how hellish existence truly is and that there is nothing appealing about existing as a conscious being who is destined to decay and die with the ability to suffer to the most extreme extents. It's truly terrifying how one is capable of feeling such immense agony in an existence that was always so unnecessary in the first place.
I don't want to suffer in any way, I just wish for nothingness, all that's ever comforted me is the thought of eternally ceasing to exist but more than anything I wish I never existed at all, the fact that humans so harmfully procreate in the first place is the most terrible tragedy.