I bet, and we (everyone but them) shouldn't have a say in their decision about keeping their lives because we're not going through with what they have to put up with every second of their life.
I don't understand why it's so hard for some people to assimilate that.
It's sad, but most likely that's one of the main reasons why it isn't allowed.
_____
I for sure know that if i had cancer or another terminal illness with no chance of recovering i would prefer dying while i'm still "whole" than slowly wither and die in pain.
I guess it depends. I lost a relative to cancer a couple years ago, she wasn't able to eat had to be fed through a tube, she seemed out of herself at times too and could barely speak.
I would definitely prefer dying earlier than that.
ALS and Alzheimer are two of the worst diseases i could think of though.