In his eulogy, Marc Antony said of Marcus Brutus:
This was the noblest Roman of them all....
He, only in a general honest thought
And common good to all, made one of them.
His life was gentle, and the elements
So mixed in him that Nature might stand up
And say to all the world. "This was a man."
While Jay Gatsby's business activities were far less than noble, his spirit was, indeed, noble. For, his idealized love for the golden girl found him pursuing an idealized persona of himself to recapture the past; it saw him building a castle for his love; it saw the noble knight standing guard in the rain for his lady, ready to defend her with his life. Yes, he was worth "the whole rotten bunch" who carelessly discard the lives of others, pursuing only their own comforts.
Jay Gatsby pursued that ethereal dream of repeating the past, that illusive dream of happiness, that graspable dream of success. His heart was gentle, and "the elements so mixed in him" that Nature might say he truly loved and walked a little higher over the earth than others. This, too, was a man.