You have been programmed to live. Everything you do is a way to fulfill that programming. Yet, some people override that programming and all their survival instincts and decide to end their lives. How unbearable must suffering be that one denies what he is made to do, i.e. live.
But suicide remains mostly an untouched subject among most. People don't even like to think about death, let alone question suicide. Inevitably, most people are unaware, uninformed.
Non suicidal people do not understand suicidal people much like how rich kids don't understand their poor counterparts. The rich kid wonders why the poor doesn't wear nice clothes and has nice toys. "Why not just ask your dad?" wonders the rich one. He believes it to be a learned helplessness (Even the poor might start believing the same if he lives among the rich quite often). Similar things happen to suicidal people. Much like how the rich one doesn't understand his privilege of wealth, non-suicidal people don't understand the privilege of hope. For both, their respective circumstances are their definitions of normal.
A common misconception among the general public is that people end their lives because something specific went wrong. That's a terrible way to generalise. It leads to people questioning, "why not just fix what's wrong or just accept it? How bad can it be?" — But I don't believe you can always point fingers to a single reason. I think people end their lives because everything in their life becomes so painfully complex that they either find it impossible to correct or simply not worth it.
But nonetheless, the knowledge gap still remains. Nobody who hasn't committed suicide knows exactly what it's like, those who have aren't alive anymore to describe it. So it stays a mystery and leads to one asking, "why not live?" and another replying, "why live?"
But contemplating suicide isn't suicide. Asking, "why live?" isn't suicide either. Asking such questions might be precursor to intent but isn't actually intent. But then when exactly do they decide that life isn't worth living? It's certainly not when they are thinking and talking about it. Because if you're still thinking/talking about it, you've not decided. Either you still hope that life is worth giving another chance, or you don't believe the pain of death to be worth it (yet). I think the exact moment is when you start making tangible plans about it. Wanting to jump off a bridge is one thing, and planning that you'll take your keys next Monday and drive to the specific bridge at the exact time when nobody is around, that is a completely different thing.
Another question that remains is when someone is ending their life, and at exact moment when they are about to die, do they regret it? When the man on the noose is struggling to catch a breath, does he want to live just one last time and realise that it's too late?
Unfortunately, I do not have an answer to that. Whether a failed attempt is a relief or a disappointment is still a mystery to me. And some things are better unsolved.