I think at first it is the fairytale of royal privilege that makes a person interested. Just like the red carpet with performers. Love to see the designer gowns, designer suits and jewels.
Diana, Princess of Wales' book made me take notice of BRF. I watched their wedding and thought what a fairytale and then the book. WOW a soap opera! The press made the BRF a major interest to people worldwide.The Duke and Duchess of Cambridge will be living in London soon and in a fishbowl. Baby Cambridge is going to much needed security. I also like other royal houses, but the press coverage of the BRF is overwhelming.
Getting back to the real reason we like royals its their work they do for causes dear to them.