In order to understand just how formidable depression is, you have to understand the anthropological origins of "moods". Our "moods" are nothing more than biological responses to everyday things that affect our health and welfare. For example, when you are sick, your mood will be depressed because in order to survive an illness and get better, you need to rest. This is nothing more than an evolutionary adaptation that is hard wired in all of us. Depression in the proper context serves an important purpose. Likewise, when you are healthy and meet a potential mate or get to do a productive activity, your mood is elevated and you are more productive and successful in your endeavor.
People who are depressed lose control of this basic biological adaptation and have their mood stuck in a depressed state. When in an abnormal depressed state, the normal stresses of life become devastating because depressed people are already down when they take on the stress and do not have the ability to regulate their moods and come out of the depressed state when the stressful event has passed.
What is really frightening about depression is that this basic biological imbalance cannot be overcome with the medication that is currently prescribed for depression. Anti-depressants treat people with depression by putting them into a constant state of an elevated mood. Anti-depressants do not restore the ability to regulate mood that depressed people lack. So, people suffering from depression often realize that the medication has taken over their mood and do not feel like they are "normal" when on medication. They then quit taking the medication and often go into an even more severe state of depression.
There is a promising movement in the mental health profession towards using long-term intensive psychotherapy to treat depression. People who have undergone this sort of treatment have reported to finally be able to properly regulate their moods and no longer get stuck in a depressive state. Unfortunately, many in the mental health profession are reluctant to take people of anti-depressants, and it is also very difficult to know when someone is so depressed that they need intensive psychotherapy, which is very, very expensive.
So, in Madison's case, the only productive lesson to be learned is that you cannot blame anyone or anything. People who are depressed can be taken out of every stressful situation and still end up trying to take their lives. Suicide ends up being the only way the person suffering from depression can believe that they can finally end the constant depressive state. Dealing with depression requires restoring the ability to deal with stress, not eliminating all stress. Unfortunately, it is too difficult for anyone other than a well trained mental health professional to know when there needs to be serious intervention. And even when people recognize the need for serious intervention, the treatment of depression is still a very slowly evolving field with a lot of missteps along the way.