* To attract Daisy: Gatsby's primary motivation is to rekindle his love with Daisy Buchanan. He hopes that by throwing extravagant parties, she will eventually attend and be drawn to his wealth and lifestyle. This is made explicit in the novel when Gatsby tells Nick, "I'm giving a party tomorrow night. You're invited, of course. I'd like to have you meet my friend, Daisy."
* To create an illusion of popularity and success: Gatsby craves social acceptance and longs for the recognition he feels he deserves. By throwing these lavish parties, he's attempting to build a façade of popularity and social standing. This, however, is largely a facade, as most of the guests are strangers who only attend for the free food, drinks, and entertainment.
* To recapture a lost past: Gatsby's parties are also a manifestation of his deep-seated desire to reclaim a lost past. He feels a sense of longing for the time he spent with Daisy, and the parties are a way to recreate that atmosphere of wealth and carefree fun.
It's important to note that Gatsby's parties are not truly a celebration of his own life or genuine enjoyment. They are a means to an end, a desperate attempt to achieve his ultimate goal: winning Daisy back. He's essentially using these parties as a stage to present himself in the best possible light, hoping that Daisy will be captivated by his facade of wealth and popularity.