Giving a gun to an insane person is as much a crime as giving an insane person razor blades and knives, or allowing an insane person to drive a car.
This issue isn't about gun ownership. It's about wreckless endangerment on the part of a steward or guardian.
Well I didn't say insane, I said mentally deranged. And many of these people do not have stewards or guardians. If you have doubts just spend some time downtown on the streets of any major city.
Should these people have a right to carry firearms?