I think the concern would be a gang buys a 3D printer and just makes guns for everyone in it. These guns are disposable and untraceable.
All it takes is one kid in school who's parents own one for him to create guns for his classmates. And while it might be a hobby for the rich, prices will be coming down.
I do think there is some overreacting in the short term. The real thing is still incredibly easy to acquire and not terribly expensive. Gun trafficking is not a dangerous business as the feds are so lax on it that you'd think they support runners. So I don't see a real high demand for it in the short term.
Long term though, who knows? These machines will get more advanced and the price will drop to a point that most homes can afford them.