Excess of many things can instigate cancer, as can exposure to harmful environments.
Your example of Steve Jobs probably wasn't a good one, because actually he developed pancreatic problems due to an excess consumption of fruit. He believed that fruit was still healthy for a body even if it's consumed at the expense of all other food groups.
He was completely wrong of course and excess consumption of fruit was the cause of his demise.
However I see what you're doing there .... as in we're all going to die in some manner anyhow and therefore why not smoke and allow that to be the contributor?
If you've ever seen someone die from mouth, lung or throat cancers, you will understand why it is such a miserable, prolonged and excruciating death. There are a million ways to die and surely you wouldn't pick that one as your primary choice?
Besides that though, even if you don't contract lung cancer from smoking, it makes people wheeze, develop emphysema, reduces your vitality and fitness level, leads to clotting of arteries /veins and is repugnant to people forced to endure your secondhand smoke.