My grandpa fell down the stairs of their farm in his sixties. He was paralyzed and needed help with everything. He slowly developed cancer over time but was for

My grandpa fell down the stairs of their farm in his sixties. He was paralyzed and needed help with everything. He slowly developed cancer over time but was forced to just lay in bed. All he did was beg for pain pills and to be set free. He complained that a sick animal on the farm would be put down but no one would help him. It was very heart breaking for a young kid to see. I get why no one grant his wish: no one wants to be the one to "kill" him and the (false) hope of a miracle. This is a complex issue: we already have DNR which seem to break the same "do no harm" ethics for a doctor.