She may claim to be humiliated by the ordeal, but Kendra Wilkinson is a sex-tape superstar — her XXX debut, Kendra Exposed, is selling like hotcakes! “It surpassed our expectations. It’s our best-selling tape so far this year and could be one of our biggest-selling celebrity sex tapes of all time,” Steven Hirsch, founder/co-chairman of the company that released Kendra’s video, Vivid Entertainment, tells In Touch. So what’s the secret to Kendra’s success? “Kendra has millions of fans that love her. There's no question that the real popularity of a star helps to sell a movie and, of course, it helps that she's only 24 years old and beautiful," Steven adds. While the bodacious blonde has become an adult film favorite, another reality TV star, The Real Housewives of New Jersey’s Danielle Staub, has not quite achieved the same level of fame in the industry. "Kendra's sex tape has easily sold four times that of Danielle's sex tape. It performed poorly, mostly due to the fact that she is not very likable," an insider tells In Touch. Though she took legal action to stop its release, Kendra’s tape hit the web in May, while Danielle’s video was released in June through Hustler Inc.