I think there is a difference between killing someone like Osama Bin Laden, who would be close to impossible to be caught and imprisoned and killing someone who is in a prison that has lots of security. As a side note, I do think we need drastic prison reform, but that's a different topic. Some, or maybe most of those who have committed mass murders are psychopaths. Psychopathy is a mental illness, as a result of damage to the frontal cortex, which currently has no effective treatment, so I don't think we should kill someone just because they suffer from psychopathy, when we have the alternative of imprisoning them to protect society from them. I think I said much earlier in this thread that I would be fine with giving someone who is obviously guilty of a brutal murder, the choice of life in prison or the death penalty. I would rather die than spend the rest of my life in prison, assuming I was guilty of the crime that I was prosecuted for.
I watched an interview of Timothy McVeigh, shortly before he was executed. He said that he'd rather die than spend the rest of his life in prison. In my opinion, life in prison with no chance of parole is often perceived as being more cruel than death. That would certainly explain why some prisoners commit suicide. How to deal with dangerous members of society is complicated. Not everyone has the potential to be rehabilitated.
As comes to people making the decision to die, I think we should afford that as an open option to just about everyone, with the understanding that it is gated not behind legal hurdles but psychological ones designed to isolate those who are merely cyclic or depressed from those who actually understand that their future is fucked, looked at it maturely and without duress and made that decision with sound mind.
I don't have a problem with that, as long as they are offered every available treatment first. In another thread, I mentioned that I had an uncle who suffered from the most severe depression of anyone I ever knew. He was in and out of mental hospitals over the course of his life. He had every available treatment for depression at the time he was alive, including EST, antidepressants, and talk therapy. He wrote a book about the history of our family, which I had hoped would help him cope. I don't know if it was ever published, but I thought it was a positive thing for him to do some research and write. The last time I saw him, I think I was about 19 at my grandmother's funeral. We talked briefly. He seemed a little bit better. Soon afterwards, he committed suicide. Sometimes depression is impossible to treat and perhaps he should have been offered a more pleasant way to die, other than by hanging himself. Nobody knew that he planned this. I have other family members who suffered from depression but I don't think any of them ever seriously considered suicide. That includes my late father. I know some disagree with us about this, but I believe in bodily autonomy, which includes the right for an adult to end their life if that is their choice. But, I also believe that we have failed those who suffer from brain disorders and that should be our first priority.
Suffering from depression doesn't mean that someone isn't of sound mind. it's just an overwhelming feeling that life is hopeless and there is no reason to keep on living. I just added that because after reading your post again, I think I may have misunderstood you at first or you might misunderstand my post. Basically, I think we are on the same page.