Wallow: intransitive verb

Definition:  to spend time experiencing or enjoying something without making any effort to change your situation, feelings, etc.

Source: http://www.merriam-webster.com/dictionary/wallow

In the essay ” The Dentist” taken from The Things They Carried by Tim O’ Brien he states ” she’ll explain how she cant understand  why people want to wallow in all the blood and gore.”

Now that I know the meaning I know the author meant that the lady couldn’t understand why people want to stay in that depression without making any effort to get past it.