Believe in the Illuminati? I am not sure what you mean by the question.
The Illuminati are a secret society, created centuries ago, I do not think that the original Illuminati are still active.
If a person was to Google search Illuminati, I am sure that person will find many organizations claiming ties to the original Illuminati.
As for singers and actors being members, I seriously doubt it as the Illuminati were never entertainers, they were more political activists.