I admire actors like Cumberbatch and Daniel Day-Lewis who immerse themselves into their characters and produce outstanding performances, but I’d never carry it far enough to start smoking. Poisoning yourself for your art is unreasonable IMO!
I don’t admire actors who have to “become the person” to become the character. Bogart didn’t do that. Jimmy Stewart didn’t do that. Spencer Tracy didn’t do that. Orson Wells didn’t do that.
It is called “acting”. You should be able to act without having to duplicate the entire life experience of the character. Great actors don’t need to do that.