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Despite all the eye-rolling pretense of hipster look-at-me-ism, there's a basic undercurrent that rings true for me: young people looking at a fragmented economy and an uncertain world are uneasy at their utter dependence on systems they have no control over. A lot of them, with beards or without, are trying to assert some small, tangible, hands-on control over the basics of staying alive. Even if it is substantially symbolic, in the broad picture, this is a good, healthy thing IMHO.
Now that you mention it, the typical late teen to mid twenties hipster's formative years included the Great Recession, 9/11, and Hurricane Katrina. It's not unexpected that as they gain control over their lives, a tendency toward self reliance and preparedness will appear.