Why so cruel?

One thing about this novel that really disturbed me was the outright cruelty with which some of the characters treated each other. On pages 146-147, within a few lines of each other, the following things are said-"Shut up. You're drunk," "Go to hell, Mike," and "Damned noble of you." Stuff like this happens throughout the entire novel. It's pretty amazing how cruel the characters are to each other, and I was wondering why Hemingway would put that into his novel, but I think I've figured it out. Hemingway seemed to be a rather bitter fellow. The way that he has the characters treat each other makes that very clear. Also, I think that he saw a certain cruelty in society, and it angered him. He wanted the readers of his time to see how the characters acted and wonder if they treated others the same way. Hemingway was hoping to make a change in his society by doing this. I think he is also challenging readers of any time to make the same change in their lives. This creates a timelessness in the novel, because it can be read and related to by anyone from any time period.