...sure, a few will escape harm if they have incredible genes. However, most will experience at least some of the myriad of side effects from emphysema to lung cancer. Similarly, accutane is dangerous on many levels, from destroying the brain's needed chemicals to bowel dysfunction to heart troubles, etc. We still don't know all it is capable of, but you have to figure anything that causes horrendous birth defects is not good for us on many levels!
Just because a VERY few aren't affected by smoking doesn't mean that cigs aren't poison for a vast majority of human beings. Smoking and accutane are far more likely to cause health problems than driving on wet roads. This is case of escaping without harm is the EXCEPTION, rather than the rule. Many who think they've escaped the side effects will likely be affected later (like Vioxx and all the other dangerous drugs they convince us only hurts a few).