Well, given that there are 30,000 gun deaths each year in the US - and 10,000 of those are homicides - that's hardly a lunatic few. It's similar to drunk driving. Hundreds of millions of people drive in the US; a tiny fraction of those drive drunk. So why have drunk driving laws? Because those drunk drivers can do a lot of damage. Thus there are laws against drunk driving, license and registration requirements, laws that drivers have to follow etc. To some people lunatic killers hold some odd attraction. Other people have fantasies of pulling out their massive handguns and blasting away at the bad guys, thus becoming a big, masculine hero. Both are pretty out there - and don't represent the mainstream.