Man is born with a number of potential emotions - affection, pride, passion, hope - some of them negative - jealousy, hatred, etc. Maturity helps him control his emotions. But maturation never completes, and no man can entirely free himself from jealousy, or even hatred.
One particular emotion man fails to free himself from—despite the best efforts of modern society—is empathy. Pure apathy remains unattainable, even in our times. One will often fail to control natural empathy when faced with animal suffering (think of a struggling penguin) or terminal suffering. When these 2 situations are combined, even wise geeks will let their natural emotions prevail.
The desire for euthanasia is as natural as empathy. The former is simply a severe symptom of succumbing to the latter. That being said, this writer is human, and is apprehensive of having to combat his natural emotions the next time he boards an aging Airbus.