Paul brings up a great point with the price of cruise ship entertainment.
Last year I was told by a cruise director (I won't mention the cruise line) that their typical "production show" - meaning the usual musical revue which I find boring - costs them around $5 million or more to get ready for presentation, and it takes them around 18 months on average to get it "ship ready". These are ballpark figures, and some shows have gone to $10 million and two years to get ready. I am not making this up.
Then you add the costs of replacing the entertainers as people move in and out of the staff, training the ship's theater staff, licensing fees, copyright fees, and all the other little things, and you can see why the cruise lines will stick with a specific show for 3 or more years, moving it from ship-to-ship before finally retiring the show.
I have no doubt that NCL has tens of millions invested in the Epic entertainment, if not hundreds of millions.