As soon as you speak, the world becomes dumb. What do you mean?

If you are a chatterbox, you won't be dumb, which means you don't talk much at ordinary times, at least in his opinion, you don't talk much at ordinary times. He thinks you are introverted, don't like to express your emotions and don't communicate much. So in his eyes, you just don't like talking. He thinks no one is less talkative than you. If you think you talk a lot, there will be no dumb people in the world.