Gold is being used for more than 3000 years ( hope I am not wrong about the oldness). But bitcoin has only one application (this application is one of biggest human creations). Without this application there will be no utility and the hype will be finally over,
gold may technically have other applications, but they represent a tiny share of its market. if it weren't valued as commodity money, the market would be worth only a tiny fraction of it current value. people don't line their jewelry boxes with aluminum necklaces and their vaults with bars of steel, do they?
bitcoin is essentially another form of commodity money. people will (and do) accept it for payment (currency) because of its underlying scarce commodity value, much like people accept gold coins for cash/trade. it's the same principle.
we don't need all the world's transactions to use bitcoin in order for billions of people to be part of the network. and that's where bitcoin derives its value from---
the network effect. back of the envelope numbers: if 20% of the world transacted with bitcoin 10 times a year, that's still ~ 500 transactions per second on the bitcoin network. that's much more throughput than bitcoin can support, even considering all offchain solutions at present, so let's not get ahead of ourselves!