Cryptocurrencies' prices are dictated both by speculation and utility. Bitcoin's price movement seems to be driven by its use as an investment vehicle with increasingly many platforms offering consumers the opportunity to hold Bitcoin e.g. BITW, and Robinhood. Much of the rest of the cryptocurrency ecosystem including Ethereum, Polkadot and Chainlink supports underlying infrastructure and decentralized applications.
Bitcoin's dominance thus reflects the extent to which the valuation of the crypto sector as a whole is driven by its investment potential as currencies as opposed to its platform potential as blockchains.