I like it.
It was a mania in retrospect, because it blew out of proportion, but there's nothing intrinsic about the asset which would have made it deterministically, conclusively obvious to a knowledgeable investigator that a crash was in-bound (beside, maybe, its biological nature; biological investments are irregular). Rather, it was unsustainable because of the price; but what price is sustainable for tulips? What price is sustainable for bitcoin?
Markets are very, very weird; probably because human behavior is weird. An undeniable axiom: Markets can remain crazy longer than you can remain solvent. And at some point, a "crazy" market isn't crazy; its just the market. Many would say that a $10,000 engagement ring is a crazy asset to purchase; yet thousands upon thousands are sold & resold every year.