I'm only half kidding. I'm a bit of a prepper and I have lots of powerbanks and devices that charge from USB but besides idling my truck I really had no other way to charge any of them in case of a long-term power outage which seemed a bit of an oversight on my part.
Not like this solves the issue. 30 watts (under ideal conditions) isn't much but it's a start.
My focus is on casual prepping as a hobby that in the worst case can one day turn out to have been useful. Actual self-reliance is a full-time job. The vast majority of people have virtually nothing stocked up. Someone who has intentionally put aside supplies for even a week is ahead of 99% of people. It takes surprisingly little to cover one's basics and anything extra is a luxury.
Being able to hunker down the first week or two is critical. Fist-fighting at the gas station is not what one wants to be doing during the early days of collapse.