Fixed period of life like all power tools. Repairing (i.e. fixing) costs more than buying a new one. That's what I call a "consumable'. Most things people think are 'capital' items (i.e. they call them "investments") are actually consumable items. Laptops, (most) cars, houses (to a large degree), electronics, etc.
They're not designed to last a lifetime. They have a fixed period of life. You can extend that period of life but generally speaking at the point that the lifetime of the item ends the repair cost exceeds the cost of replacement. Granted that period of time varies; with a house it might be 50-75 years and most people won't be alive long enough to realize that it is indeed a consumable. If the value goes down with age (wear & tear) it's basically a consumable; your use is the consumption.
I see what you're saying, but the end result of this is that practically everything is a consumable. You might as well buy the cheapest/just good enough of all power tools, appliances, musical instruments, cars, a house...in short, everything but financial instruments(given the avoidance of a currency collapse) and raw land.
In the world of
www.consumablesjournal.com, practically all tools are bought at HF on sale (which really are decent enough for most use), all clothes are bought at thrift stores, all cars are old four door Toyotas, the Sysco-truck fed restaurants are just the thing.
Alternately, you can accept that some people buy 'better' stuff just for the sheer pleasure of it or because it's 5% better than something that's 1/4 the price.
Now, whether a $23 used German heat gun will last longer (or less) than the lowest end new heat gun is an interesting experiment. It's a pretty small amount of money to risk.