The Subversiveness of Existentialism

In apologetics, when you're talking to people who just, they don't believe, I think it's important to clarify. What is our culture being catechized to believe is the ultimate problem today? So for example, I just watched a movie, Everything Everywhere All At Once, Nine Oscars, Winning Film. And the villain in that movie has succumbed to nihilistic thinking. Well, nihilism is just like so what do it ever?