Some people just have the will to commit crime. And those people will exist until the end of time. Having said that, then there are those that have no problem murdering another person to get what they want. Firearms are simply one means that they use to do that. What the anti-gun extremists don't get is that banning firearms isn't going to change that.
Anti-gun zealots will attempt some form of logic by suggesting that while people will murder, banning guns will reduce their murderous rampage to just a few individuals if all they have are knives or machetes in which to kill their victims. Apparently they are unaware that people have gone on rampages with cars and just ran people over to commit mass murder. And of course there are the home made WMDs, aka IEDs, that people have manufactured. If a person wants to commit mass murder, they will find a way, but liberals are too narrow minded to get that.