There is no insane investment you can't say that about. Those metallic-cover special issue Marvel X-Men comics they used to "limited collector release" in the early 90s will eventually be of enormous value to archaeologists in the future, too.
Illiquidity is a bad thing, not an generally an indicator that something is an especially good investment.
Also your tendency to define things in binary terms (liquid/illiquid, value/no value) is troubling.
Why the struggle to pretend not to be able to tell the difference between Bitcoin and limited edition comic books?