Yes, all the people who kill other people (except in self defense) are crazy. That argument of guns don't kill people though is a bad excuse for keeping everything the same imo, since you don't know who the crazy people are until they do something crazy, you'll keep risking (the lives of others and your own maybe) and allowing them to have guns, even though the guns by themselves don't kill because they're unanimated objects.
I agree that guns (and other tools/instruments) don't kill but the people using them do. The thing is that some of those tools/objects kill with little to no effort and require no experience or high amounts of money to get and use. Guns are probably best option for crazy people because they're relatively cheap, they were developed to kill as quickly and efficiently as possible without getting your hands dirty and they're legal (in the US more than anywhere else).
There are tens of thousands of deaths by gun violence in the US and mass shootings are not as uncommon as we would like. Unless you think the USA has a lot more crazy "evil" people than in Europe (I don't thing that just to be clear), there's no way around of the fact that guns are part of the
problem. If you do, then I rest my case.