Can massive amounts of porn over years ruin your sex drive for females? How true is yourbrainonporn.com? And are all of those people just in denial?
If electroshock, ex-gay therapy and other horrible procedures can't change your sexuality, then porn certainly can't either. Yes, there is some evidence that show that the type of porn you watch can affect what you are attracted to, but this has little to do with your sexuality. But short answer: Yes, most of those people are in denial.