I have a question for you: how can we determine gold? After all, is is just a name which human create for an object. And over a period of time, it has been raised and adopted by human as one of the most valuable asset on the world
Same thing is happening to bitcoin. We use digital gold to name bitcoin which makes it becomes even more valuable.
The OP describes bitcoin as a digital gold because of its rarity and price. Yes, we, humans named or coined the term gold and bitcoin so that we can distinguish the thing we have to describe.
Actually, he did not say directly that bitcoin is a gold. He just want to emphasize that bitcoin is valuable enough so that we might also see it as valuable as gold. Bitcoin is valuable and volatile, it can be an investment or asset that we can store over a period of time. For me, bitcoin can become gold when it comes to value and rarity. And it is also a digital currency that may destroys the fiat as time goes by.