Most of the gunfighter's were from the South who had fought in the Civil War or were Southern sympathizers. They were from families that were well respected and some were very wealthy before the war.
The end of the Civil War and the killing of Lincoln , brought harsh treatment the southern states. Most of the people's possessions were either lost or destroyed during the war and what wasn't lost was usually taken away by the carpetbaggers, during what was suppose to be reconstruction.
Most of the Gunfighter's were ex soldiers turned Gamblers and Bandits. Some were pushed into becoming what they were. Some were just born to kill.