I had a student in a class once that had this opinion that a student should get an A just for showing up for class. Uh, no. A possible reason for him being in school in the first place is that his parents made him go, due to the implication that he will be thrown out of his house if he fails. Also, check his other classes. What kind of grades is he getting in them? Failing or passing ones? If failing, then it's no surprise. If he's passing, it's possible he doesn't like the subject matter of your class. Nevertheless, you've warned him that he will fail. For now, all you can do is watch and wait. Bottom line, you can only motivate so much; the rest is up to them.