I think people are disappointed in the movie because they are one-minded, meaning their thought process led them to.. the owner is going to come home, and, or he’s watching him from a back room and he’ll eventually come out.
He’s in this luxurious home with millions of dollars worth of art, also with state of the art tech, the dream home. But it comes down to, you can have all the fine things in life, but without water, food, a shower.. running water.. the bare life essentials you have nothing. Shows that everything else is luxury and you don’t need a lot to live.
The fact that he accepts this is how his life is now, while still trying to ways to escape, and also enjoyed the luxury of living in a world he never experienced before explains to me that you should accept what you have right at this moment but never lose hope of wanting better.
This movie is SURVIVAL.