Candidly, I think you're wildly oversimplifying things. When it comes to mass shootings like this, you are generally talking about people who are legitimately "bad" or "crazy", and handling a weapon in ways that no one would assert are legal. While there are indeed many in the pro-gun camp who do like the 'tough' feel associated with a gun and shooting something, honestly, the marketing underlying that is really no different than the marketing associated with buying an SUV, and an infinitesimally small number of the people who respond to it actually raise said gun against other human being. (And while not nearly morally equivalent, I'd bet a substantially higher percentage of SUV owners handle their vehicles aggressively vis a vis other drivers.)
Freedum? Sure. For better or worse, it's in our society's founding documents. And for that reason, probably more worthwhile to focus on the hard work of generating the consensus to change those founding documents via the pathways provided. Because short of that, you're probably left with the comparatively easier path of dealing with the bad or crazy people. And of course, if you do take the hard path, you probably still have to deal with the bad/crazy people anyway.