I don't think that people who are depressed are consciously choosing a selfish or easier strategy when the reach a suicidal point, any more than I think that people who are AS are consciously choosing to be socially awkward.
None of us can determine how powerful another's pain is, for them as an individual. I respect everyone's choice to do the very best they know how, until they know better. I can't be angry with someone for not knowing how to take the next breathe of life. And it really does get to that point, for some. Other's have known pain, yes. But if you have come through it, it means it wasn't felt to the same degree as the person who needed to escape it so badly that death seemed the only way.
If people in that state were capable of thinking rationally or could see a way to get better, they wouldn't choose suicide. It would be wonderful if they could ask for help sooner, but asking for help doesn't come naturally to some people, especially depressives. So, if anything, if you know anyone who really seems to be in control most of the time, never asks for help, and then goes into a depressive state...the key is to encourage them to ask for help.
Of course, we then get into the debate about what kind of help is available. Someone who is suicidally depressed may not be able to engage in therapy. But anything that gives them a gap to get over the worst of it, even short-term medication, I figure at least gives them a window to then go back into the world and work on other strategies, like 12 step groups if they are drinking or using drugs (very often goes hand in hand with suicide) or finding meaning in their lives (logotheraphy comes to mind).
These strategies will hopefully replace the medication, and the suicidal person has given themselves a chance to live another day. I guess that's why I'm not immediately anti-medication in certain situations - but obviously not as a cure-all for bad days or down moods. We all have those. But to be suicidal, there is far more happening for that person that just a bad day.