Odd things I've seen promoted for prepping
One of the oddest things I've ever seen promoted as a prepper item is an alcohol stove. There's tons of ways to make them, some quite elaborate, some very cheap, all of them impractical. The question that I have is, just how much rubbing alcohol do you have on hand at your place? Probably not a lot. While it's possible to make rudimentary adult beverages like tizwin, scrumpy (higher than normal hard apple), raisin, maple, persimmon wines, it's relatively difficult to make moonshine without exact temperatures and distill a high enough percentage of ethanol without ALSO making non-drinkable and poisonous similar compounds like propanol or methanol. They also come over at similar temperatures. Regardless, if you have this ability, I doubt you'd waste it by burning it in an alcohol stove. If you have the ability to make alcohols of all kinds in a SHTF scenario, then you're probably trading it for premium goods. That's a historical fact.
Endless varieties of knives
I really don't get all the wasted time and effort on the latest great knife or knives. You probably need a skinner, a pocket knife for fine work, a large hacking knife or even a machette or ax or hatchet. That's it. Why ruin a good knife by using it improperly and breaking it, when it's probably better to use a hatchet's blunt end or a hammer instead? Why spend a fortune on this piece of equipment when there's lots of knives that have been used in field work and bench tested? It boggles the mind.
Endless varieties of guns
You can spend a lot of money on these. No doubt one will have more takedown power along a long continuum. Unless you plan on buying many different kinds of odd ball ammunition and parts, and have endless amounts of funds, then it's really a waste of time. You want something reasonable that has a good reputation, common ammunition, relatively decent takedown power and accuracy. Practice shooting instead. Most people don't.
Making your bug-out bag lighter
Oh boy, this one pisses me off. A bug-out bag means that you had to leave and that you're trying to get to specific place that has more security and supplies. Instead of endlessly replacing equipment to get it lighter and lighter like some high tech backpacker, learn some skills instead and find ways to bug-in. This is a serious time waster unless you live in a highly urban environment, and even then, if you're bugging out with a million people, I doubt you make it.
Really? You might be able to shoot accurately with practice and stealth. I have no doubt of their efficacy as long as you're actually healthy enough to walk around for miles lugging it. They are quiet though, but some of the weirdos depicting hunting with it, I doubt they can sneak up on any creature regularly. Has it's place, but only if you can fashion a dart yourself like they do in the bush.
The latest gadget
Learn skills instead. Usually they're expensive.
The lightest tent
Ummm, obviously you've never burned nylon tents with hot coals or seen them rip from lots of UV sun exposure. Buy something that will hold up. Learn how to patch it. Better yet, learn how to make a debris hut, learn how to make survival cement and branch shelters, dig out a shelter, etc.
Buying endless amounts of freeze dried and or MREs
This is guaranteed the most expensive way to prep. You should have some. Many freeze dried have very little fat, and hence are low calorie meals. Not good for survival, is okay for healthy backpackers or mountain climbers who're taking a short trip. MREs are great as long as you buy the actual military issue, not some ersatz kind that actually doesn't provide enough calories. They're very expensive, but it means fast meals often without fire, which has it's place for security. Unless you're uber-wealthy, no one can afford all MRE prepping. Maybe can you own.
Very fancy butane/propane torches
Why not learn to use a long lasting tinderbox and flint(chert)/steel device instead. It's way cheaper. It'll work when other things won't. These torches are expensive and what will you do when you run out of fuel?
Buying a fancy compass and not knowing how to use it and map skills. Nuff said.