You can see a scenario where someone without a serious mental illness could just snap. I don't see why we need assault weapons, or even handguns.
The Second Amendment is designed to prevent government tyranny. But in reality, small arms (even assault weapons) are going to have no effect against government forces. A machine gun doesn't matter against napalm or planes with missiles.
More's the point, when, in the last 50/100 years has a violent response to government tyranny resulted in the reinstitution of democracy? If you look at the places where democracy has grown, it's always grown out of peaceful protests, not violent ones.
The places where a well armed militia has fought with the government have turned into atrocity ravaged hell-holes (e.g. Congo, South Sudan, Columbia/FARC).
The reality is that the Second Amendment is an anachronism. The guns are just used by citizens to kill other citizens. I understand "rah rah I'm a Celtics fan..." But "rah rah I'm a Democrat," or "rah rah I'm a Republican," is just stupid. Don't take a position just because "my party believes..."
Think for yourself.