First of all, before taking another nomadic step, I suggest you take out some time to understand how NFTs work, how NFTs are initialized on a chain, and lastly, how NFTs are minted for sell on a blockchain market.
To cut it short, the INITIALIZATION AND MINTING of an NFT on any blockchain marketplace comes a cost that is determined by the network selected by the creator. These fees do not in any way accrue to the revenue treasury of the marketplace. it goes to the miners that help sustain the network.
I hope this explanation helps