There are many reasons to kill yourself; the idea that suicide is bad in all circumstances is a strictly Judeo-Christian notion. Falling on a sword instead of betraying your principles and burning yourself in a town square in defiance of a corrupt regime are two examples of worthy suicides. Suicide is also a way to regain your honor if you have committed a great injustice such as the rape of a woman or committed treason. It is nobler for a traitor to take his own life than to be imprisoned or executed for his crimes: this act shows true remorse and true integrity of character.
It is better to end your life if you are being forced to do something which compromises your character or dignity. At all times we are the captain of our fate, one only truly dies when he can no longer control his destiny, when he can no longer end himself. A fate far worse than death is one in which we lose control over our actions, decisions and judgments, the only three things we ever have control over in the first place. Suicide is a reassuring option that reminds us that we are mortal and everything can be endured in one fashion or another.
We speak of unendurable terminal illness and the great pain it causes being worthy of suicide, so why should the exits from a similar pain of a mental sort be any different? Those who can find no solace in the strictures of the society or can find no use for themselves in a real, meaningful way – also suffer a form of illness, usually terminal. It is an unpalling anguish born from being honest and living in western society and as a consequence having no possible future that is fulfilling. Why should someone who has no desire to live be legally forced to? Life is not universally precious and it is not the domain of external agents to judge it as such.