Gold bugs are literally defined as people who hold gold and view it as the best investment possible, regardless of the state of the gold market. This is something that is extremely irrational, and probably deep rooted. Thus, it's extremely hard for one to just "give up".

Though, I do think that with cryptocurrencies as a viable alternative store of value, especially bitcoin, it would only be a matter of time before gold perma-bulls start converting some of their long term holdings into bitcoin. I've seen many youtubers do so over the past few years, and this trend will continue, but will take time.

It may ultimately not even come down to gold's market cap, but rather, the rise awareness of better alternative store of values like bitcoin that has the exact same properties as gold, that makes these gold bugs shift their investment stance.