Does it have to be just one reason?
Life can be a lot more complex then that.
I can wish I had never been born, based on things such as being told that I am here, because of rape and a failed abortion attempt, long before legal abortion, and how I shouldn't be here. (by some parts of family) Then told how much I remind them of criminal elements in the family, that they taught you the skills to kill if it ever came to it, yet those same skills, they then compare you to what they taught you to fear. I see no reason to have kids that your going to horsewhip the evil out of them, yet still tell them they will always be evil? I only saw the need for self removal, if I ever actually became the danger, that family has told me I would be. That wouldn't even deal with the fact most suicides, tend to leave stuff that the family will have to deal with, such as clean up, etc (emotional scars on them, certainly, there are those that are innocent in this)