It's that simple physicality which gold bugs will always value, so I don't see your argument persuading them that bitcoin is *now* better than gold, and even in some future where bitcoin dominates - people would probably want some of their portfolio in gold.
I think we essentially agree.
I'm not arguing that people now trading want bitcoin as much as they want gold (that is manifestly untrue). More, I'm trying to counter the opinion that goldbugs seem to hold that there is something inherently valuable about gold, and something inherently bad about bitcoin.
That just isn't true; their argument is essentially anthropic: gold is valuable because it is valuable. There is no reason we can't say $COMMODITY is valuable because it's valuable. Therefore bitcoin is valuable because its valuable.
I don't seek to disprove the worth of gold; I seek to show that if gold is valuable, then bitcoins are valuable.
Now... a quick word about "lower bound of zero". If you want to argue that gold has a non-zero lower bound, fine, but then bitcoin must have a non-zero lower bound. It has properties that make it worth
something. Even if that something is $0.000000001. In that case we're simply talking a matter of scale not of truth.