At first it is a choice, but maybe a forced choice at your weakest. Once addicted it is a choice to get help, but it took me ages to get rid of nicotin and thank God pot made me throw up, so I never got addicted to it, but I was addicted to benzo's and normally that it also not fun to get rid of, but I quit at once and God helped me. Way easier though than heroin I think.
By the way it can also be someone else's choice, like with a pregnant mom and a kid.