So by that logic, the police shouldn't have guns because they can turn into non-law-abiding citizens as well. There never was a point in history where people who obeyed the law of the land were outnumbered those who don't, with the exception of revolutions (Which, the people of those lands deemed those laws to be unjust anyway). Pulling guns off the table has shown to only worsen violent crime conditions, while areas with large amounts of civilian gun ownership have shown to be the among the most peaceful in the nation.