That's technically true. Less than 10% of life-long smokers will actually develop lung cancer, which is considered the most commonly associated cancer with smoking. Of course, life-long smokers still heavily increase their risks of other comorbidities which will heavily increase their risk of death. That is why smoking and obesity are such great comparisons. It isn't that likely that the majority of obese people will die from diabetes. However, obese individuals will accumulate many other complications (i.e. high cholesterol, high blood pressure, increased risk for cancer) that will increase their risk of dying or, at a minimum, decrease their quality of life.