This looks like a artificial scarcity means of creating value. Vicuna wool is not particularly finer than alpaca wool, but the rarity of the former means a cost increase in the exclusive luxury market, so the owner can say, "it's vicuna" at social gatherings. It's probably no more difficult to raise alpacas and vicunas then Cladoir sheep, the latter being a fine-wooled local Irish breed.

So if you start paying the Andean villagers a lot of money for vicuna wool, all their neighbors will start raising vicunas, because who doesn't want to get rich raising sheep in the mountains? Then the market would be flooded and nobody would pay top dollar for not-so-exclusive vicuna anymore (the villagers probably know all this, but don't have access to direct-to-consumer marketing for more competitive pricing - get them a Starlink Terminal and ah, err, Tiktok account?

Fashion is a funny business, more about social science than economics. Incidentally wool demand might be rising due to microplastic concerns over synthetic fleece clothing.