This might fall under living will as well. Yes for me and for many I know when pain is unbearable, a cure is not forthcoming and I cease to enjoy life and to make those I love happy it is time for me to go.
Let the money be used for someone else, let me go to where ever I am going.
Death will come to all. There is no escaping it. So if one can end ones life on a positive note, say their goodbyes and pass along some joy and wisdom yes it is time to go.
Why wait for what more pain and agony? Let me slip away in the company of loved ones..............
Actually most people if they are at home and have access to simple over the counter meds can take matters into their own hands.
As the French say "Sleep a little death"