Why does Ecclesiastes 10:20 warn not to curse the king even in your thoughts?

Answer: A bird may carry your words

"For a bird of the air may carry your words, and a winged creature may report your speech."

“Do not curse the king even in your thoughts, or curse the rich even in your bedroom, for a bird of the air may carry your words, and a winged creature may report your speech.”— Ecclesiastes 10:20 (BSB)