There have been a lot of interviews with people who committed suicide (and failed). Most of them said they did not plan it and it was a last minute decision.
Don't want to argue the logic of suicide too much, but isn't that a self-selecting audience of people that didn't plan well, and hence "failed"? There are plenty of people that take their own life that spend quite a lot of time thinking about it, and planning.
That sounds not very rational to me.