Who is The Man from Buenos Aires from Tevye the Dairyman and the Railroad Stories and what is their importance?

The Man from Buenos Aires is wealthy, but has some big international business which is never defined. He is like the man of air, who makes money in a mysterious way out of nothing. This man is a romantic figure, who is returning to his home village to marry a hometown girl. The reader also asks whether he is actually some type of criminal or lunatic.