This statement became quite clear on page 92 when Daisy began to sob as Gatsby “took out a pile of shirts and began throwing them, one by one.” It was at that point in the novel that Daisy realized she could have had happiness and money if she had just stayed with Gatsby, despite him being poor at the time.
Instead, she gave into her materialistic desires and chose security over true love, and that cost Daisy her happiness.
What money can buy is material items such as clothing, jewellry, houses, goods, and cars. That idea was made awfully apparent by Jordan on page 78 when she explained the reasons behind Gatsby’s disregardful shopping. He “bought that house just so that Daisy would be just across the bay,” and was able to afford throwing extravagant parties every weekend. Notice again here that in the end, his money did not help him acquire neither happiness, nor Daisy’s