I used to believe the same, but now i'm rethinking that stance. When it comes down to actually performing the deed and making it permanent, those who go through with it truly believe the world will be a better place without them in it. They feel they are holding other people back from reaching some potential or causing grief that would not be present with them gone. Sure, the trauma short term is rough, but they feel in the long term, it's better that they can no longer interfere or be a burden.