Yes but the amount of amber, gold, silver, etc. on Earth is a known unknown. There are presumably deposits of gold that we don't yet know about. The amount of BTC is known. You seem to be conflating rarity with fixed scarcity.
> Using existing anti-money-laundering laws & global institutions, you'd be effectively banned from getting back any value from your BTCs (or, doing so would expose you to all the associated risks).
While this is true, this is sort of the whole point of bitcoin. Like, it's a currency that is independent of any nation-state and acts as a sort of systemic-hedge against governmental incompetence/malfeasance. So the fact that it could even be banned by any particular country is kind of part of its value proposition. And, similar to VPN's, just because an IP-based technology is banned doesn't mean that it'd become impossible to use.