You can convince people with facts and logic but they have to be ready to have an open minded conversation and you have to talk on a subject where they can actually do so. If a topic is somehow precious to someone or they get easily frustrated, they can just talk themselves in circles indefinitely or get angry and leave. But you can find gaps by asking questions. For example, the lemmygrad poster that was screenshotted includes that they compared Marxism “in the real world” compared to capitalism, which already means they don’t even know what Marxism is (it is not an economic system lol). I’d ask them to define Marxism and then start talking about its actual meaning from some other angle, e.g. ask them what they read. It definitely wasn’t Capital.