That is patently false.. By definition criminals do not follow the letter of the law, a good example being that murder is already illegal. Strangely enough though, it still happens. Weird right? So would it also make sense that even if guns are illegal that maybe some bad actors would still have and use them in an illegal manner? Disarming law abiding citizens is all you're doing. Full stop.

Hunt, catch, and disarm the criminals too, like murderers. Then when we catch the criminals with them, we take the guns and destroy them. Illegal things happen but over time with proper enforcement they happen less. Such effort requires sustained unified community effort and political commitment without playing games for votes and lobby dollars, which is the most unrealistic and impossible thing of this whole scenario.

If we can keep nuclear weapons out of criminal's hands we can keep anything out of criminal's hands, it's just a matter of doing it correctly.