Euthanasia is performed every day, the difference is we just don't call it that. When ever an MD "pulls the plug" on a life support system we in essence have euthanasia.
Always remember that the rule is that you as an individual have no power, but a major corporation or financial institution can do nearly anything.
If an insurance carrier refuses to pay any more for a patient on life-support the insurance carrier in essence gives the medical facility the order to end the life simply by refusing to pay the bill for maintenance.
There are times were we are more kind to our pets than we are to other human beings. In the 1980's I had a great friend who died in a hospital in St. Paul MN of complications from HIV. His death was one of the most horrible I had ever seen and since that time I have only seen two that were worse.
The next was also an HIV patient that developed non-Hodgkins Lymphoma cancer. The HMO refused to pay for any treatment other than hospice care for this man and he was placed in a hospice. At that time they denied him even comfort treatments to make his end better. This man literally drowned in his own body fluids when a treatment was denied. I was there several hours before his death and watched as he lay there gasping. Again the HMO refused to do anything else.
The final HIV death of a third and wonderful friend was from a condition called "PML" which is an abbreviation for a huge word. The death starts from a complete liquification of the brain and starts with a series of strokes usually. This fellow was one of my best friends. I watched him lie in a totally vegitative state in Cedars in Los Angeles for a week before the process progressed enough to end the torture. This death is portrayed in the movie "It's My Party" which starred Gregory Harrison and Eric Roberts.
There are circumstances where euthanasia is a good thing because it ends suffering. I have seen cancer patients in such pain that even opiates did not kill or deaden it sufficiently.
Yes, there is a time where existance is far worse than death.
I do not know the legal or religious ramifications nor would I want to argue or debate them. What I do know is that I have seen lingering and painful death multiple times in my life. I have seen what religious individuals would define as "life" be sheer torture with people screaming in pain for days on end.
In my own case, if I were to be placed in this situation I would want a painless and merciful death rather than that kind of existence.