I think you have a reading comprehension problem. The smoking/cancer analogy was not a comparison. It was used to state that you should not dismiss good advice simply because you think someone is a hypocrite.

| exploiting and completely depending on others’ labour

Ralph Waldo Emerson was Thoreau’s friend and he allowed him to stay on his land. How exactly is that exploitation? When your friend does you a favor or lends you something that in your mind is exploitation?

My guess is that you have never read “Walden” or “Civil Disobedience” or “Life Without Principle”.