You have posed an interesting question regarding human nature. In a similar vein, why do people eat things they know are not healthy for them? Why do people fail to get enough sleep or exercise when they know if is necessary for their wellbeing? Why do people exceed the speed limit in driving when they know if is against the law, and may be dangerous?
The response for all of these questions seems to me to be either that there is no good answer, or that there are as many answers as there are people doing these things.
I note that your question was indirectly addressed in another question that came to JVO. It was:
I don’t think that there is any better answer to your question than was given in the responses to that question. Though there are excuses that could be offered (it is a habit, people are addicted, the harm is long-term and not immediate, etc.), and one could point out that the history of these behaviors predates the knowledge that they are unhealthful, there is really no good reply that can be given you that deals with Jewish values, morals, ethics, or derekh eretz (proper behavior). Consequently, I don’t see a value in asking for additional responses from rabbis on this site. I suggest you take a look at the answers provided in the question noted. If you have another question that you wish to pose that is more directly related to Jewish values, ethics, morals, or derekh eretz, please feel free to submit it to JVO, just as you did this one.
Thank you for asking.
Answered by: Rabbi Joseph Blair