Someday, a space mining company is going to unload a shit-tonload of gold mined from some asteroid onto Planet Earth. And then, what happens to that ancient 'store of value' that thrived on scarcity once it stops being scarce?

OTOH Bitcoin is capped at 21 million coins, eternally. What would be a better example of scarcity at that time in the not-so-distant future? What then should be better entitled to the title: "store of value"!

The threat to Bitcoin can never be from Gold or any other commodity; neither from fiat. It can only come from competitor coins, or from deranged government action assisted by terrifyingly accurate intelligence.