The other interesting but useless fact is that silk top hats (which as the article points out supersede beaver as the fibre of choice) are no longer made - and the technique for making them is effectively lost because they need specialised looms which are also no longer made.

But if you want to go somewhere super fancy like Ascot and look the part, a silk top hat is de rigueur.

There are now a handful of shops that basically have the entire remaining (good) stock and rent them out for an arm and a leg, and take care of them like rare precious things. Which I guess they are.