One of the morals of the story "The Bet" concerns a lesson on human folly and pride. Folly is when someone makes foolish choices. In this story, the characters of the banker and the lawyer are so prideful and arrogant that, to prove their individual points about solitary confinement, they sacrifice important things in their life. Because the banker felt angry that his views on death being preferable to a life of isolation were being challenged, he risked two million rubles to prove his point. Because the lawyer wanted to prove his point that any life is better then death, he sacrificed fifteen years of his life in isolation.
In the end, the results of their prideful and foolish bet have terrible consequences. The lawyer loses his desire to live on earth and comes to hate the normal pleasures of human existence. He says in a letter to the lawyer:
I despise your books, despise all worldly blessings and wisdom. Everything is void, frail, visionary, and delusive as a mirage.
The lawyer says in his letter to the banker that he will give up the money he would have earned on winning the bet and leave five minutes before the bet would have been completed. This allows the banker to keep his money; however, in the banker loses his own self-respect in the process. He realizes how foolish he was to make such a bet just to bolster his pride. He knows that he has ruined a man's earthly happiness forever, and he despises himself for it. The story says that never before had the banker "felt such contempt for himself as now."
In short, this story warns the reader of the dangers of impulsiveness and pride. The thoughtless choices individuals make in the heat of emotion can often have devastating, life-changing effects.