Lots of them, not a few. Ethereum,︂ Cardano, Solana, Cosmos, Monero. In fact, many shitcoins are technologically better than BTC.
Adoption is︃ not a solid premise to call BTC a hard currency or digital gold, because a︄ new angle or gimmick can make people drop BTC and adopt the next shiny thing.︅
Say Amazon starts accepting cryptocurrencies for payment. But they only accept Solana. Well a lot︆ of Amazon buyers will then get Solana for the first time, the speculators would watch︇ SOL moon and they'll jump on the new bandwagon. So that's one possible scenario where︈ BTC is usurped. But it can happen in all sorts of ways.
Unlike gold, which︉ is a natural resource found across the universe for 7 billion years*, not a piece︊ of code written by a human that will be old fashioned like the radio in︋ no time. BTC code already looks old and it's only been a dozen years or︌ so. Technology is a bad platform to use as a store of value. And a︍ store of value is not what BTC was designed to be.
Yes a truly decentralized︎ currency can only be invented once, but that doesn't mean the BTC as the first️ can't be usurped. Social media can only be invented once, but where is MySpace now? Even Facebook looks vulnerable to getting surpassed by competitors these days.
*Even gold looks precarious, lab grown diamonds have caused the price of diamonds to drop in value, and there is talk of lab-grown gold coming. Something to watch out for.