Usually when a person commits suicied it is not because they want to end their own misery or make others suffer. The reason a person commits suicide is because they believe they are doing what is best for their loved ones and the world in general. Most of the time when a person is suicidal they are also dillusional. They truly believe their loved ones will be better off without them, that everyones life will be so much better and easier without them there to mess it up. Usually when a person decides to commit suicide in their mind they are making the ultimate sacrifice. They are willing to die for the what matters most to them.
I am not trying to glorify people who commit suicide or claim that it is some kind of heroic act. I'm just trying to help people understand the "reasoning" behind it.