There is a certain similarity to many of the back-stories relating to first-offense DUIs. Indeed, many people had just one more drink than they normally do or thought they had waited just long enough for their body to metabolize the alcohol in their system.
The incredible weight of a criminal charge can make it very difficult for anyone to try to move on from this unfortunate chapter in their life. They made a mistake and they want to learn from it -- but they can't because of the stigma they carry as a result of their criminal charge. The literal punishment from the offense can sometimes pale in comparison to the indirect consequences of the offense: an inability to retain or find a job, the loss of their driver's license, and difficult finding a suitable place to live.