The last word on a sad subject

Amy, over at A Place to Talk About War, makes it very clear that she believes suicide is wrong and inappropriate, and that she is firmly opposed to it. Having established that principle, she points to the horrible tragedy in Glendale as evidence of the fact that suicidal people often couple homicide with their efforts, whether on purpose or not:

If, however, some people are determined to end their own lives, can't they please manage to do so in a way that doesn't take other people with them? Because this man in California was 'despondent,' he parked his SUV on the train tracks, setting off a wreck that involved three trains and killed 11 people who were not despondent and had no wish to die. And to top it off, he had second thoughts and jumped out of his SUV at the last minute, so he's still alive!

I wonder whether, when people commit suicide, their thinking process is so deranged (otherwise, why commit suicide?) that their unable to see the logical consequences of their final actions, or whether they really do intend to bring other people down with them?