Their carelessness is absolutely influenced by their money. Money lives within Daisy, as Gatsby discovers when he describes her voice.
“Her voice is full of money,” [Gatsby] said suddenly.
That was it.… That was the inexhaustible charm that rose and fell in it, the jingle of it, the cymbal’s song of it.…
Fitzgerald has manifested a personality for money, in the character of Daisy. She uses this charm to get what she wants, and to escape from situations she doesn't. After Gatsby leaves, she marries Tom, and it is heavily suggested that it was because of a single expensive necklace that he won her over. While she maintains her illusion of loving Gatsby to escape Tom's cruelty, in the end she returns to Tom and her safe, wealthy home. The sadness is that Gatsby recognizes this tendency in her, and so all his efforts are on acquiring material goods to impress her. The moment when she cries over his shirts, saying “They’re such beautiful shirts,”.… “It makes me sad because I’ve never seen such—such beautiful shirts before," highlights her own shallow, materialistic nature and Gatsby’s pathetic, transparent efforts to impress her.
Jordan Baker is affected by her wealth in that she retains a cold detachment from everything. When she first appears , she is lounging on a sofa with Daisy “as cool as their white dresses and their impersonal eyes in the absence of all desire,” like two queens in a world of illusion. Jordan uses and disposes of Nick, similar to Daisy's use and disposal of Gatsby. She lacks true morals, and she is confident that her actions don't matter, as long as everyone else is looking out (see her comment on "never meeting another careless driver.",) and her world revolves around herself and false material values.
Tom Buchanan is perhaps the most affected by his wealth. He is the most immoral, racist, unsympathetic character in the novel. He is cruel, arrogant, and has theories about old money and new money which set him & his polo buddies apart from Gatsby's lot. He is from an “enormously wealthy” family, he and Daisy spent a year in France and “drifted here and there unrestfully wherever people played polo and were rich together,” before ending up in East Egg. Tom is demeaning to George Wilson, his mistress's husband, and one can sense that he almost enjoys toying with him while sleeping with his wife. He also mistreats Myrtle herself, whom he violently hits in front of her sister and Nick when she mentions Daisy's name. But he keeps his wife in the end, and leads George Wilson to kill Gatsby with no consequences.