Criminals are afraid of being shot just the same as a normal, non-criminal citizen. They want to avoid starting trouble with those people they know have a weapon by which to protect themselves. The criminal is only hoping the government will remove the guns from the law-abiding citizens so they can rob, rape and plunder at will without fear of reprisal. Of course the criminals will not turn loose of their guns.
Perhaps the educational system during the late 1700's was much better than our current, modern one. Since it is obvious the founders of our nation were wise enough to include the Second Amendment knowing that each American needed the means to protect themselves against foreign and domestic violence. Today's politicians, especially those on the left, seem not to have learned the same information as our early founders seemed to know. And we call our current politicians "progressive." That is just another term of which they have changed the meaning.