Its very true that sometimes celebrities like to speak their minds about the issues in the world that are important to them. They like to call attention to social or political causes. They understand that their position as a public figure gives them a unique advantage.
People listen to them. Other people, like Sophie Turner at P Diddy’s Grammy after party, prefer to use their clothes to make a statement. I think. I’m assuming Sophie was taking advantage of the fact that she has a gorgeous ass that everyone wants to stare at by slapping a peace sign on it to make a statement about peace. Of course, she may have just thought it was cool or, more likely, her stylist thought it looked good on her and told her to wear it.