And every copy of Bitcoin, with a different starting seed, is also scarcer than gold. That doesn't mean it has value.
Nobody said that forks of bitcoin have value because of scarcity.
The value of something is not determined by rarity, that is irrelevant
This is clearly relevant I rather say. Supply and demand determine the market value. Limiting supply to a finite number with a programmed inflation, regardless of the demand, influences the market value.
when bitcoin is long gone there will still be gold.
Um, proof?