If you or someone you know is contemplating suicide, one of the best defenses is to think about the harm you would do others. You will bring misery to everyone who loves you.
What you may not realize is that suicide is contagious. People close to someone who has died by suicide are often tortured with suicidal thoughts for many years afterward, and dream that the person who is gone is waiting for them to come join him or her.
Think of sucide as two murders. Self-murder and the possible murder of someone who copies you.
The person who copies you may not be a close friend, but someone who knew you who identifies because he or she is also depressed or bullied or addicted. You have set a bad example.
It is a touching sign of human altruism that people in great suffering often do hang on because they don't want to inflict pain.
It is also important to remember that there are more than 10 times the number of attempts as deaths by suicide. Never give up on someone, saying "He'll just try again." Never give up on yourself.
Suicide is a choice we make in moments of great distress, sometimes when facing troubles that will go away, more often because of major depression and addiction that may still be treatable. When it is not treatable--and this seems to have been the case for David Foster Wallace and Spaulding Gray---suicide is the only path out of a future that rationally promises only pain. Psychic pain is not different morally than other kinds of pain. But do not confuse temporary pain with permanent pain, even if it seems endless.