work in an/(one's) ivory tower
To reside or exist in a place or among a social circle that is characterized by effete academic intelligence and thus is out of touch with or aloof from the realities of life. I don't put much weight in the advice of a bunch of economists working in their ivory towers—they've never had a real job in their lives. It seemed easy to solve all the world's problems when I was working in an ivory tower. Now that I'm not a professor anymore, I realize things are so much more complex than I'd imagined.