I think you brought up the main factor to BTC becoming a reserve asset; confidence. To regular people not familiar with crypto, BTC is just digital play money. Its value is what people decide it is. Unlike gold that has a lot of real world uses like technology, BTC doesn't. So for it to become a reserve, it needs to be used/recognized by different countries, companies, and governments.
Unlike gold that has a lot of real world uses like technology
Other metals actually have more real world uses so that doesnt substantiate gold's price. The fact is gold is no different: people have confidence in that. If that waned, the price would crater.
Other metals actually have more real world uses so that doesnt substantiate gold's price
I think it is Gold's perfect balance of scarcity and use that makes its price go up. Sure there are metals that are better conductors and cheaper, but gold experiences the least corrosion, and can be made to be very thin. So for those looking for quality in electronics, pure gold, and gold plating is the way to go.