Why are they involved?
If a famous person is found to be highly intelligent and has compiled knowledge in the political arena, then I am interested in hearing what they think about the upcoming election. Otherwise, they are just trying to parley their fans and followers into believing propaganda.
Celebrities have the time, money and the connections to become highly knowledgeable about politics. They are extremely affected by some of the laws and taxes politicians push forward, so a political interest is cultivated. Their well informed opinions, rife with first hand knowledge are welcomed.
Some celebrities play doctors, lawyers and other smart people roles and it goes to their heads. “I’m not a doctor, but I play one on TV.” is a great example of the grandiose ideas actors and actresses can delude themselves with, in their minds.
Martin Sheen is a great example of this nonsense. When he is on film indorsing Biden and the Democratic party, he acts very somber and presidential. His statements are authoritative and strong. I think he actually believes his political opinions should carry more weight because he pretended to be President Josiah Edward “Jed” Bartlet, on the TV series The West Wing. There is no indication that Martin knows anything exceptional about our political system, apart from the script lines that he had to memorize in the filming of his character.
Compare Martin Sheen to Richard Dreyfuss. Dreyfuss has long been interested in politics and history. At one point he considered running for Senator. His politics are tied to his love for history, and he has somewhat become a history scholar. He founded The Dreyfuss Civics Initiative. https://thedreyfussinitiative.org/
When Richard Dreyfuss speaks about politics, he is indeed calling upon his fame and fans to deliver a message, but it is based upon the history knowledge, that he obtained apart from acting. His opinions should carry far more weight than anyone riding on fictional character knowledge.
Taylor Swift is easily dismissed in this political climate. Why would someone listen to her opinion? Turns out, maybe we should! Taylor has inside information because of her dating relationship with Robert Kennedys son Conor. She even moved into the house across the street from Conor. She truly likes Robert F Kennedy Jr and would not be inclined to oppose him or his political agenda. Now that he supports President Trump, she will likely stay mute about her politics so as not to alienate any of her fans.