I disagree. While that may happen, I wouldn't assume it in every case. Concurring opinions of a number of qualified physicians should be had before prematurely coming to that conclusion. Deciding a person lacks legal capacity is of great significance, and should only be done within the strictest of standards and procedures.
I submit that a person faced with a terminal illness who holds no real hope of recovery and has nothing to look forward to but an extremely painful and lingering death, may logically and of sound mind come to the conclusion that a quick, peaceful and painless death is preferable. That is unless the person is a masochist or has religious reservations.
In the meantime, the time on Earth for the terminally ill, absent the life-saving procedures, can be made less painful with the use of morphine and the like, so that he does not feel unnecessary pain.
Funny you mention that. The very government that would deprive you of your decision to die, will also deprive you of pain relief. And both for the same reason: Your life is not your own. Due to the WoD, aggressive pain treatment has suffered tremendously, as doctors are afraid of arrest.
We can sit here all day and dream up "What if's". For a real-life example, I urge you to read post #137 of this thread:
That requires the complicity of the state. You make my case for me.