SOL tokens are valuable for a few reasons. One of them is that they are used to pay for transaction fees on the Solana network.
They are also needed to become a validator node on the Solana network. To become a validator, holders need to stake their SOL tokens and there is no minimum requirement for staking.
They can also be used as a trading asset. SOL tokens are listed on many exchanges and they can be used for trading with other cryptocurrencies.