Yeah I have zero intention of experiencing dementia from a first-person perspective regardless of what my government has to say on the matter, if I outlive my wits then something has gone horribly wrong in my view.

What culture won't be sickened?

The problem with that thinking is that you're thinking now as an outside observer who can look at your mental decay and say "that guy should kill himself". But, when you're in the body apparently it's different. My friend's dad died of alzheimers, it took more than a decade.

At first he was just a bit forgetful and absent-minded. But, he was still driving, doing woodworking projects, taking care of his grand kids, helping around the house, etc. Then he had to give up driving, but he was fine taking the bus, and he just made sure to have his cell phone on him all the time in case he needed some help. He even took a camping and hiking trip with my friend and his kids later in the process when he was regularly mistaking people for other people and couldn't do much anything unsupervised. Eventually he had to go into a specialty care home.

At what point in the process would you, as an outside observer, think "ok, it's time to kill yourself"? And, do you think he felt that way in his own head? Even when he had noticeably diminished capacity, he still enjoyed spending time with his family and friends.