Why does narrator call lawyer unhappy man In the story the bet?

In Anton Chekhov's "The Bet," the narrator describes the lawyer as an unhappy man because, despite winning the bet and gaining wealth, he ultimately becomes disillusioned with life and the value of material success. His isolation during the years of imprisonment leads to profound existential contemplation, revealing that true happiness cannot be bought or won. The lawyer's experience illustrates how the pursuit of wealth can lead to a deeper sense of emptiness and despair.