Even if that were true, it would account for perhaps 1% of the sales of such weapons in the US. Everyone else is just playing with them, and fantasizing about how when the nation collapses they're gonna show us all who the real 'alpha males' are. In fact, they're so into this fantasy that many of them are hoping for the collapse, and even trying to bring it about.
The insane gun fetish in the U S is mostly due to the gross and pervasive emasculation of white males over the last 50 years due to runaway capitalist greed and a reaction by everyone else to the poor results of white male leadership of the past. Millions upon millions of "regular guys" who fancied themselves the alpha males of their society and culture have been turned into little more than the low-paid lackeys of a few very clever, greedy, arrogant, and amoral corporate tyrants and their rich upper class capitalist investors. Most of their wives make more money than they do. They are no longer anything even close to being an 'alpha male' in this culture and they are very angry, and very resentful about it. But there isn't anything they can do about it because money RULES ALL in this culture and they don't have much of it. Nor will they ever have.
So they buy lots of really scary looking, powerful military style guns and ammo and they go out and play with them on the weekends, imagining that they are all Rambos; showing the world who's really in charge when they get "pushed too far!" Guns are sacred male totems in this culture, now. Which is why no logical argument on Earth will stand up against men having them as an absolute right. It will never matter to these men how many innocent school children are murdered. Those guns are their only real, tangible, claim to manhood and they ain't gonna give 'em up, no matter what.