Pantalone has been smoking for 300+ years, for a (very) heavy smoker like him to take smoking out of his daily routine is just as severe as losing an arm. Smoking has been a constant in practically every stage of his life, this is just worse than losing both legs for him
So to quit smoking all at once means that there’s a catalyst that has provoked it, a sudden traumatizing event or a fatal diagnosis that prevents the user from smoking. Pantalone has gone through both. He has his days counted.
