The victims in The Grapes of Wrath are the common people, the people who are at the mercy of the moneyed class. We see this in the fate of the Joads. The Joads are sharecroppers, who lease their land from wealthier landowners. When the depression and dust bowl hit, the land is no longer profitable for sharecropping, so the tenants are kicked out.
Part of their frustration is in their failure to understand the nature of their problem. They do not understand how the land cannot be theirs when they have lived on it for generations. In some cases, they no longer know who owns the land that they are being evicted from. Banks and holding companies are consolidating wealth and financial power, but they are faceless and unapproachable. They also do not understand the environmental situation that has devastated the land. When the dust bowl conditions persist, all they can do is stand and watch the dust swirl and crops wither away.