Why does the narrator call the lawyer an "unhappy man" in "The Bet"??

There is an omniscient third-person narrator telling the tale, but he does not call the lawyer an "unhappy man." The narrator, who is telling the story through the banker's point of view, has the banker call the lawyer an unhappy man. The omniscient third-person narrator is quoting the banker. The exact words are as follows.

"Think better of it, young man, while there is still time. To me two million is a trifle, but you are losing three or four of the best years of your life. I say three or four, because you won't stay longer. Don't forget either, you unhappy man, that voluntary confinement is a great deal harder to bear than compulsory. The thought that you have the right to step out in liberty at any moment will poison your whole existence in prison. I am sorry for you."

The story was originally written in Russian, and we are reading one of several English translations of Chekhov's story. The Russian word that is translated here as "unhappy" must have had a slightly different meaning. The banker seems to be saying, "You unlucky man," or "You unfortunate man," or even "You misguided man."

The banker himself regrets getting involved in this fantastic bet. He will have to keep the lawyer a prisoner on his own estate and will be aware of his presence and his presumed suffering every day. He wants to get out of the bet, but he is too proud to ask to be let off himself. Instead, he is trying to persuade the lawyer, a younger man, to call the bet off. Obviously the banker is telling him, in so many words, that all he has to do is ask to be released and the banker will immediately forget the bet was ever made.

In calling the lawyer an "unhappy man," the banker is "projecting." He is comparing the lawyer with himself. The banker is an extrovert, as is shown by his holding a big party and by his ostentatious display of his material possessions. He does not realize he is dealing with a different type of character. The lawyer must be an introvert. Once he becomes a prisoner, he immediately sets to work to make himself comfortable in his solitude. He orders a piano and learns to play it. He orders six hundred books over the years and learns a number of foreign languages in order to read them. The banker is the kind of man who would go completely crazy in solitary confinement, which is why he already considers the lawyer an "unhappy man"; but the lawyer adjusts to his imprisonment without any apparent difficulty.

Like anything else, like quitting smoking for example, the first days must be the hardest. But solitude might become natural after a certain term, at least for some types of people. Henry David Thoreau wrote in Walden:

I find it wholesome to be alone the greater part of the time. To be in company, even with the best, is soon wearisome and dissipating. I love to be alone. I never found the companion that was so companionable as solitude. We are for the most part more lonely when we go abroad among men than when we stay in our chambers. A man thinking or working is always alone, let him be where he will.

In the end, ironically, it appears to be the banker who is the unhappy man. The lawyer is not necessarily happy, but he has achieved something like nirvana. He feels spiritually enlightened and content.