I'm not confident of an economic collapse. However, ANY cause for the federal government to declare martial law will be sufficient. It's also possible the UN gun laws may attempt to be enforced on U.S. citizens. I am certain of this, if anyone tries to take guns away from U.S. citizens, many will comply. Many will resist. And resistance with guns will be bloody. The equivalent of civil war in the country. You don't buy billions, literally billions of bullets, including millions of hollowpoint, along with tanks, unless you think you will need to use them. To quote a Ray Bradbury book, something wicked this way comes.