Everything is valued by how much people are willing to pay for it (barring governments introducing ceilings/floors/fixes) even if it has no intrinsic value in of itself.
Please describe an object with "intrinsic value" based on your definition of it, exclusive of what people are willing to pay for it.
Food? Show me an example of bartering your food to buy a new PC, please do. Food has zero effective value in most cases, and no intrinsic value except in the special case of someone starving.
Shelter, or land? Again, it's all about what people are willing to pay. Land in a desert in the middle of nowhere has no value, land in a highly desirable city local has a huge value, but this is simply because of demand and market forces, not any "intrinsic value" as you define it.
Fact: such objects do not exist. Nothing in this world has a value in the absence of what others are willing to pay for it.
Your definition is interesting philosophically, but it is useless for real discussion because nothing actually fits in it.
Also, as a simple test, look at gold. Gold has no intrinsic value based on your definition, so is gold fiat as well? You are arguing an absurd argument IMO.
The term "fiat" is used to distinguish the difference between government established currency with no backing vs naturally occurring currency that backs itself, such as gold or silver or now bitcoins.
Bitcoins have VALUE, they don't have an intrinsic value.
Your opinion. I disagree. They have a tremendous intrinsic value in allowing distant near-instant transactions without requiring trust of any central 3rd party. This is incredibly valuable, and handles a need that can not be fulfilled by any prior technology or physical product.