Aside from your strawman form of question, you would not know the now ex-gun control advocate Democrats that I know who bought weapons if I named them and I wouldn't out them anyway. They are still Democrats but no longer anti-gun. Their fear has nothing to do with "black people invading their homes". Their fear is the multi-racial radicals (overwhelmingly white) who are burning shops, seeing the police not controlling the destruction, and the call to reduce the police forces that they had relied on to respond if they ever had to call.
Again, that is a right wing fantasy. No "die hard Democrat" would be spending much time exposed to such propaganda, much less allowing it to hijack their animal brain and turn off their frontal lobes to that extent. They are more likely afraid of the police and Trump's federal thugs, if they're truly afraid of anything regarding wanton violence in our country.
It really sounds like you're just making stuff up or at the very least exaggerating to make it appear that right wing fear mongering is a reality that even "die hard Democrats" would buy into it.
You are too warped by ideology to know how most of the world lives. Right-wingnuts and left-wingnuts are the most vociferous so get most news coverage, but even combined, are a minority of the American people. Most real people (dem., rep., and lib.) get along fine, calmly discuss politics, and accept each other's political leanings.
Your "us vs. them" mentality is sick.
Both sides are not the same. Our polarized politics reflect human minds. They don't exist outside of what our minds create. Cognitive, perceptive, and psychological spectrums are not the same on either end. There's not equal tendency toward violence on both ends. There's not closed mindedness on both ends. Both ends are not steeped in fear. Both ends are not authority-worshiping.
At this particular point in time, everyone may be behaving badly under stressful circumstances, but not all of us, I would say less than half of us, are subsumed to an authoritarian "law and order" cult. Not all of us have the same tendency for animal brain fear aggression. Not all of us believe whatever we hear as long as it appeals to our prejudices. At this particular point in time in the U.S., it is the Dem party that most closely represents principles of fairness, critical thinking, and a working sense of right and wrong.
That could change, of course, as ideologies change and morph just as people's minds do. After all, ideologies are products of our minds. Hell, in Australia, they call their right wing authoritarian political cult the Liberal Party. Funny how tribal names rarely tell you anything about the tribe. You have to look at what they stand for. Do they allow power and authority to be punitive and without accountability? Do they stick up for the powerless? Do they live in a mindscape where minorities are savages taking over their white washed world? For now, in the United States, as I said, the Dem party most closely reflects actual American values of equality under the law and humane principles.
Both sides are not the same. Right wing extremism is way more violent, way more heartless, way more bigoted, way more scared, way more frightened of the world outside their ideological bubble, way more likely to absorb whatever their authority figures tell them and act on that information indiscriminately. I could go on.
Your cartoon of "die hard Democrats" buying firearms to defend themselves against a right wing fear fantasy doesn't hold water. It's comical, in fact.