I feel there are so many individual cases that it's hard to set guidelines. Should only those in great pain be allowed to die by their own choice, and only if they have no "quality of life"? I think that is defined somewhere.
Until we personally have experienced these situations it's hard to decide. My uncle survived many years with brain tumours and many surgeries, and was allowed to die in his forties. Operating would have killed him, not operating killed him. It was rather clear cut. At my cousin's wedding he forgot I was his neice and he hit on me. The surgeries caused brain damage. He suffered the consequences mentally and physically. He died about 3 years later. The last time I saw him he looked 90 instead of 40. He could not see, he could hardly move, and it was still a very slow death.
Yet he was not in pain. He lived his last months out in a hospital that took care of dying patients. If he had been in pain on top of everything else, it would have made it a hundred times more horrible. His brain deterioration didn't allow him this torture, thankfully. I still wonder what it was like for him to slowly waste away like that. He wasn't there much mentally, but how much did he feel or know about his condition?
Now my son's dad is deteriorating the same way. Slowly slowly. His family still lets him drink. He can hardly hold a glass. He still manages to get a cigarette to his mouth, shakily. It takes him an hour to button a shirt. But he's not in pain. It's painful to watch though.
What would that be like? Not as bad as being wracked with pain and having to live on painkillers. Mind, the painkillers can zombify you the same way as those whose brains are wasting away.
Yet life is life? What is it to someone who is in pain and dying? Is life still too precious to give up? Why? What is it like to be living like that? How can we judge until we truly know?
That's why I can't really decide. IT may be worse than dying, or it may just be the last few days, months, years of life. Life. Is it worth suffering a pain we personally can't feel until we have to experience it? Then there is a depression factor. In this case it can be a merciful feeling of letting go when living in pain. Or do you have to be depressed to feel suicidal? I often wonder about depression and why we experience it.
Afterall, a dying person in tough times would be taking up resources that healthy people need in order to survive. Depression would allow them to let go easier, to accept they are dying. Thus assisted suicide is more merciful than starvation or getting caught by a predator. Well, I would rather a peaceful death over a suffering one like THAT.
So I look to others who have had experience with these kinds of things. I just think we have to look at all the variables of each case individually when making such a decision. That really tough to do too though.