Both of these texts feature characters that have more money than they reasonably know what to do with and also no moral basis for their actions or decisions. As a result, the novels present these characters as being able to run amok in a world, doing what they want without fearing for the consequences of their actions and not caring anything about the lives of those who cross their path. This accounts for Nick's assessment of Tom and Daisy at the end of The Great Gatsby:
They were careless people, Tom and Daisy--they smashed up things and creatures and then retreated back into their money or their vast carelessness, or whatever it was that kept them together, and let other people clean up the mess they had made...
In the same way, similar attitudes can be seen in The Sun Also Rises in the way that Brett becomes involved in Romero's life and the drunken antics of the Americans as they travel around Europe and live their debauched lives. Jake for example describes the drunken fight that he has with Cohn as a "game" and the characters are depicted as wandering around European countries aimlessly, ruining both their own lives and the lives of others they come into contact with.
It needs to be remembered, however, that this frustration depicted in the lives of some characters as a result of having too much money and no moral basis for their actions, was not a cultural norm shared by everybody. The lives of the Wilsons for example, and people such as Romero remind the reader that such frustrations were the property of the privileged few rather than the many.