There is an excellent documentary called "The Bridge" about people committing suicide by jumping off of the golden gate bridge in SF. Given the height of the bridge, it takes 4 seconds before you hit the water, and some people survive it. They had interviews with people that survived it -- and they basically all said that as soon as they let go, they realized it was a mistake. That all of their problems were solvable, except for the one they just made.
I do recall one man who did not survive, who seemed at peace during the video of his fall -- he was one who I think perhaps did not regret the act, but was the extreme outlier in that regard. If you are 85 and dying of painful cancer, I can also see it being an act that makes sense, made to decide one's own fate. But MOST people seem to grow out of their suicidal phases, and realize it was the wrong choice, driven by bad thought patterns. In the same way that people try to help addicts or people with eating disorders try to obtain better thought patterns, suicidal ideation seems to me to be largely a broken thought pattern we should help people overcome, not an individual decision one should respect.