I find it interesting that it's always the more low-profile people who tend to go to these things and show their love for Harry Potter. Dan and Emma are probably the two biggest young stars of the series, yet they hardly ever go to HP-related events, aside from the movie premieres. And when it comes to the adult actors, it's always the bit players who were barely in the movies at all like Nick Moran, Warwick Davis, Natalia Tena, and Helen McCrory, rather than the big prominent actors like Michael Gambon, Maggie Smith, or Alan Rickman.