Certain people in Hollywood are anti-gun for the same reason people we know are anti gun. They where taught by their family, friends, co-workers, media and/or the educational system to believe guns are bad. Also Hollywood, like many affluent social circles has certain beliefs one most follow to be considered to be part of it, much like many actors are big into Global Warming, and being anti-Bush. It just happens that the film industry, and the acting profession general tend to have a very high concentration of people who subscribe to the progressive movement. It attracts very progressive minded people. There are also some more conservative anti-gun actors in Hollywood, such as Sylvester Stallone and Clint Eastwood who probably are that way because the have been around Hollywood politics too long. Though there are celebrities such as Bruce Willis, that are pro-gun but don't advertise it since it would negatively influence their job.