Uno to Oxnard

After Uno's father talks to him about moving to Oxnard with him, Uno cannot keep Oxnard out of his mind. The only requirement for Uno is raise 500 dollars. He finds trouble getting a job and looks for Danny to help him hustle kids. After the first failed hustle, Uno tells Danny that he gained a job as a bus boy saying he'll "have the money in no time." The two start hustling again but start doing it successfully. Near the end of the book, Uno says he's almost got $500. A few hustles later they finally loss to one the nations top prospect. At the end of the book, Uno is short of $500.
I wonder why he didn't make it to $500? With the hustles and the job it seems  it would be easy to make $500. He makes no mention of quitting his job, he just didn't gain enough money. I feel this is a mistake that Pena made. It is an unexpected ending, but I feel it is unrealistic. The final hustle was the only loss of money, maybe he found a way to blow his money and just not mention it. It does provide a debatable topic considering it from a logical stand point.