An unhealthy lifestyle is a lifestyle that increases your chances of becoming ill. If you smoke, you have a higher risk of getting cancer. Regardless of you getting cancer or not, your risk is increased. It has been proven that cigarette smoke contains substances that can cause cancer and the biochemical mechanism how these substances interact with your DNA and can turn a cell cancerous has also been proven. There is a certain propability by which such a reaction happens and another propability that this reaction happens in a place in your DNA that makes the cell grow abnormally. It should be obvious that having more of these substances in your body will increase the chances that these reactions occur and the chances that they occur in a crucial place in your DNA. It should also be obvious that smoking more cigarettes means consuming more of these substances. Therefore, if you smoke, you have these substances in your body and your risk is increased even if you never get cancer.

Another example. I have three balls, one is red, one is blue, one is green. I put them in a bag and you pick one without looking. If you pick the red one, you win, if you pick one of the others, you lose. This way, you have a 33% chance to win. Because I’m nice, I remove the green ball before you pick one. You now have a 50% chance to pick the red ball and win or pick the blue ball and lose. You have bad luck and pick the blue one. Does that mean removing the green ball was not a nice thing to do, since it didn’t make you win the game?