the man who bought the shadow of the tree

Long, long ago, in a certain village, there lived a very old zelkova tree. The tree was huge, and its shadow was long and wide. Whenever the people in the village were tired from plowing the fields, they would sit in the cool shade under the tree to enjoy the shade.
One day, a young man passed by the village and saw everyone resting under the shadow of a tree, so he also rested his legs under the tree.

At this time, an old rich man suddenly appeared, and angrily chased away the people who were enjoying the shade: "Get out of here! How dare you come in here? This is my tree shadow!"

So the clever young man came over: "Then can you please sell me this tree shadow? In this way, I can sit as long as I want, right?"

The old rich man agreed without thinking too much. Unexpectedly, as the sun slowly set to the west, the situation gradually became unmanageable...