You're probably correct, but these are times of great uncertainty and I wouldn't currently be willing to lay any bets one way or the other.

There's nothing wrong with exercising design skills to address living without reliable (or any) electricity. If nothing else, it's a hobby and keeps your mental juices flowing. If such bad times never happen, you still get the benefits that come with such projects. If they do happen, such skills can become invaluable. And there are many parts of the world where the reality is that something like this could be practically useful right now.

Designing for lack of access to global supply chains that currently exist makes this more of a design exercise rather than a practical solution. That is to say, with money, just buy a couple hundred watts of consumer-grade available solar (eg by Jackery; not a collection of no-name eBay special parts that you need to be an electrical engineer to setup), a solar inverter, a large battery pack for storage, and then a charger for battery packs for tools, instead of an air compressor-based system and this bicycle thing. This is practically useful right now, and can be ordered via HomeDepot.com. Yes, this is harder to arrange without access to HomeDepot, which most of the world doesn't have, and it's not the cheapest of systems, but a) that's a lot of bicycling; b) solar power is finally here and accessible and c) as long as we do have access to global supply chains, might as well use it.

If you're really worried, buying a bunch of backup/spare parts in case we do lose global supply chains seems like a far more viable solution. If you're really that worried about losing access, there are steps you can take, like buying copper plates and photo-resist to make your own, really shitty solar cells, from "scratch", or buying 18650 lithium ion batteries and a 3d printer (along with a plastic recycler) to print your own tool batteries from renewable plastic. If bad times never happen, then what of what practical use is it to know which wild plants in my area are edible and which ones are poisonous, or which storage unit has 10 years worth of MREs inside?

People are free to invest time and money in whatever hobby they want, and in case of global (or local) calamity, my prepper friend is my going to be my first stop. I just personally don't believe it's an especially useful hobby, any more than, say, my hobby of Lego building, which has super useful practical applications in my daily life as a Duplo builder for my nephews.

(Just as a preface, I'm not actually a prepper at all and don't think that civilization is about to end. But I do enjoy at least being familiar with ways to accomplish things in the absence of infrastructure.)

> just buy a couple hundred watts of consumer-grade available solar [...]

For my own disaster preparedness, this is exactly what I've done. And I use it when I go car camping. But, as you point out, it's not exactly cheap so is less suitable for parts of the world that are more likely to suffer from infrastructure breakdown (or are lacking the infrastructure entirely).

But there's also an undeniable appeal to knowing how to accomplish things like high pressure air when you don't have electricity at all.

> If bad times never happen, then what of what practical use is it to know which wild plants in my area are edible and which ones are poisonous

I think that there's great value in knowing things like this even if it's not of practical use to you. Like knowing how to sew & repair clothing even if you never need to make your own clothes. It's amazing how often knowledge in one domain can give you insight into solving problems in other, completely unrelated domains. The more in your mental hopper, the better.

> I just personally don't believe it's an especially useful hobby

Sure, depending on what you mean by "useful". I think that all hobbies are useful in some form, even if that use is just exercising your brain.

He's probably a typical person that looks at the dire conditions in his mismanaged small locality, and thinks the entire world is like that.