According to the studies, the largest demographic of gun owners in the US are white men living in rural communities. Research shows, that the reason they are buying guns is fear.

WHY AMERICANS ARE BUYING GUNS

Although gun ownership is associated with positive attitudes within the "gun culture", most studies comparing gun owners with other people suggest that fear is the motivation to buy a gun. While long-barrelled weapons were initially used primarily for hunting and other recreational purposes, research in the United States Dating back to the 1990s has shown that the most common reason for owning other weapons, including pistols, is self-defense. Research has also shown that the decision to purchase firearms is largely motivated by past victimization and / or fears of future victimization.

Original text of the study.