Out of all of those scenarios you laid out, banning guns won't stop them, that is what you are failing to grasp. Gangs will still get their hands on guns, home invaders will still get their hands on guns, racist police officers will still have guns, school shooters will still get their hands on guns, people who want to kill themselves, if they can't get a gun will do it another way. Don't know what you are even trying to prove?
No it is laughable that with one example I just completely disproved your point. You can be a sensible peace loving human and still own a gun.