In 1971, the Stanford Prison Experiment was created to investigate what happened to people psychologically when they are given power over others. A group of volunteers was taken to a mock prison. Half of the volunteers were assigned roles as prisoners, and the other half were assigned roles as prison officers.
The experiment was scheduled to last for two weeks but had to be abandoned after only six days. The experiment was abandoned because the volunteers who were acting as prison officers started abusing their powers. The officers subjected the prisoners to humiliating strip searches. They put the prisoners in hoods and chains, starved them, put some into solitary confinement, and humiliated others in various ways, like, for example, making them clean filthy toilets with their bare hands. The conclusion of the aborted experiment was that, when given too much power over others, people tend to abuse that power and act cruelly.
In the story "The Man in the Well," a group of children discover one day that there is a man stuck down a well. The man asks them to fetch help, but the children decide not to. When the children realize the power that they have over the man, they begin to abuse that power and treat him cruelly. They pretend to the man that they have sent for help and that help is on its way. By choosing not to get help for the man, they willingly subject him to days of solitary confinement. Eventually they get bored and leave the man to die.
The conclusion of the story is much the same as the conclusion of the Stanford Prison Experiment: when people are given too much power over others, they become drunk with that power and begin abusing that power to satisfy their own cruel, sadistic impulses.