be/live in a dream world
From Longman Dictionary of Contemporary Englishbe/live in a dream worldbe/live in a dream worldIMAGINEto have ideas or hopes that are not correct or likely to happen If you think that all homeless people have it as easy as me, then you are living in a dream world. → dreamExamples from the Corpusbe/live in a dream world• If you think he'll change, you're living in a dream world.