Father's a chronic smoker and drinker who won't quit his habits because they are his "happiness". Should I even pay for his medical bills once serious disease comes knocking?

Problem/Goal: My dilemma is whether I should take care (financially) of my father should the inevitable serious disease happen because of his vices. I feel like as his child, I have this innate obligation to take care of him, but at the same time, I find it unfair to be put in such a financial hellhole when he made the mess himself.

Context: My father is a chronic smoker, an alcoholic, and we recently found out he is a diabetic. He doesn't want to take medications, doesn't want to go to the doctor, and wants all money given to him to go to his vices, and says that his vices are his "happiness". I myself am diabetic, and one time when I checked his blood sugar as a favor, it was much higher than mine, but he refuses to see a doctor, or take any medication. Needless to say, he is in the worst shape of his life, and he's approaching seniority, which means that serious illness is just on the horizon. I worry that he will expect me to pay to make him well again, but I am just not in a position financially to shoulder that kind of medical bill.

Previous Attempts: We have tried intervening multiple times, but he just laughs it off. He gets upset and walks out whenever we try to talk of trying to get him to quit. As a measure, we tried to get him on vape instead of cigarettes, which, I know, one bad vice in trade for another, but if he won't quit due to nicotine at least take the smoke factor out of it. He remains immovable in his love for his vices.