How does Fitzgerald use Gatsby's parties to present a satirical portrait of the Roaring Twenties?

In F. Scott Fitzgerald'sThe Great Gatsby, the narrator Nick Carraway accompanies, yet stands apart from, his very wealthy and very immoral friends, the married couple Tom and Daisy. Tom and Daisy and their many rich, shallow friends, care nothing for one another; their lives are spent going from one lavish social engagement to the next.  Gatsby house is one of their most frequent stops.  Gatsby serves his guests the most expensive dishes; the champagne flows freely all night and into the mornings in his mansion with its marble floors and crystal chandeliers.  As Nick discovers when he attends his first Gatsby party, however, Gatsby's guests are not his friends. 

Nick finds Gatsby all alone by himself, away from his guests.  They are simply using him, and he allows them to do so in the hopes that Daisy will be impressed with his fortune and leave Tom to be with him.  In short, the parties thrown by this self-made man--Nick discovers after Gatsby's death that he came from the humblest of beginnings--are a waste of money and effort: Daisy will never love Gatsby because, money or no, he is not of her social class.  So his attempts to impress her with all he has achieved are for naught.  The twenties, a time of plenty, in which men like Gatsby made their millions, was less a time of success than it was a time of excess.  Spoiled and idle, Gatsby's partygoers treat Gatsby and each other as expendable.  All they care about is having a good time.  So the plenty they have is not appreciated or conserved; their wealth destroys them emotionally, spiritually, and physically.  They treat one another as if they are disposable, like the money they spend so quickly.  The parties show a society that seems on the surface to reflect happiness and prosperity, when really, it is a society in moral decay.