Why did I have to pay gas fees for a failed transaction?

What is the gas fee?

Gas fee is a type of transaction fee that you have to pay for miners or validators to make a transaction, in which, gas is a unit of measurement for the amount of energy the computer needs to use to perform a specific transaction on the network: finalizing transactions, validating them into blocks, and securing the blockchain.

Why did the transaction fail and you had to pay the gas fee for that?

When a transaction fails on the network, you are still charged for failed transactions because it still takes computational power for miners to validate and execute your transaction. So you have to pay for that regardless of your transaction going through or not. This is not a fee that Coin98 receives so we cannot refund it.