I heard on the radio this morning that Nashville had over 600 guns stolen from people's cars last year. In Memphis, it was over 1,200. The Tennessee Department of Investigation says that more than 4,000 guns were stolen from cars in 2017. A state congressman who voted for the law that made it easier for people to keep a gun in their car said, "It didn't cross my mind that we would have that many stupid people with weapons in their cars."
After Missouri passed a law making it easier to carry a weapon, St. Louis and Kansas City saw increases in guns stolen from cars. "'We have had groups of individuals that are really breaking into cars just looking for weapons,' says Capt. Renee Kriesmann, commander of the downtown district of St. Louis where the thefts have been most common. She says thefts are especially concentrated in parking lots around sporting events."
My guess would be the people stealing guns are those who have had their Constitutional right to legally own one stripped away from them. Remove the barriers to legal gun ownership for certain segments of the population and gun thefts would probably go down as well. The idea being that making guns more accessible legally takes away ones motivation to steal them from others.