Your argument basically boils down to 'we have so many guns that there's no point in trying to reduce the number, so we need more'. Perhaps you have just passed the point of no return with regards to them, but if so that's something to be deeply ashamed of, not proud of.
No that isn't common sense, that's just nonsense. The entire justice system is built on the principle that penalizing bad behavior is a logical way to reduce bad behavior. There is no such thing as this cartoon 'criminal' who will just do any bad thing they can get away with, wants to hurt anyone they can, and is not concerned with consequences. A few extreme people might be found who fit those descriptions, but acting as if its a generalized definition of a criminal is kindergarten level thinking.
If you suddenly make the penalty for shoplifting 20 years in jail, then you'll see an awfully huge drop in shoplifting rates. We don't do it, because its totally disproportionate, but it would certainly have a massive effect. Similarly if you make possession of a class of weapons carry a very steep penalty, then even amongst criminals you'll see a steep decline in them carrying those weapons. Because the penalty starts to outweigh the potential benefit to them. Just like when RICO laws were enacted, you saw lifelong Mafioso suddenly start ratting out their buddies, simply because potentially spending the rest of your life in jail really does act as a sanity check for most people.
If someone is selling small amounts of drugs or stealing a few cars, they're probably looking at a fairly low jail time if caught. If also carrying a gun means they face an extra decade or more inside if caught, many of them simply won't do it.
Oh and those people who claim to be law-abiding citizens but who declare they wouldn't give up their guns if the law was changed, give me a break. Actually pass that law and face them with 10 years inside for breaking it, and watch as most of them do a rapid u-turn.