What if I rephrase the question?
Is the act of addiction without attempting to stop immoral?
For a whole person to be immoral means weighing up every aspect of their being - something I have niether the tools, time or inclination to undertake.
Am I immoral because I smoke?
No - I have morals, I act on them, I care but I'm also far from perfect.
Is smoking immoral?
It has few positive outcomes, it is likely to cause harm to those I love, it is certainly self centred - so yes I think smoking is immoral.
But I am not immoral.....