Outside of the outright scams and meme coins, the speculative value of most cryptocurrencies stems from the same belief that if (or once) the revenue levers are turned on, they will generate a lot of usage and revenue.
Ethereum is valued at $x,xxx per token because of the belief that more and more dApps will launch on it and everyone who uses them will have to buy Ethereum.
Uniswap's UNI is valued at $x per token because of the belief that once there is regulatory clarity, UNI holders will get a % of the revenue generated by Uniswap (currently over $100M/year).
These are basically startups with tokens. Some of them will go bust. Some of them will take years to monetize. Some will be profitable within a year.