It is clear that Gatsby's tale of rags-to-riches has a certain fairy-tale element to it, and it certainly is hopelessly Romantic. It reports how Gatsby has transformed himself from a humble Midwestern boy to an East Coast celebrity. He, however, has also transformed Daisy Fay, within his own imagination, from a Southern girl to an ideal of radiant beauty. The novel is packed with references to magic and to enchantment, and, at least within the confines of his own mind, "The Great Gatsby" is an accomplished magician. This title carries a suggestion of the showmanship of stage magicians, who practise an art of illusion and use such names to advertise their performances.
So, it appears to me that there is a profound ambivalence in Fitzgerald's attitude to the imagination. It can be seen to work magic and make ordinary life seem enchanted; or it can be seen to generate illusions that keep harsh realities out of focus and help perpetuate injustices. Therefore when we think about Gatsby's autobiography as he relays it to Nick, we are perhaps slightly sceptical of the Romantic tinge that he gives his transformation - a scepticism that the rest of the novel bears out.