Or someone already has tezos and uses them to buy ... @QuipTalk

Answer: If someone already has Tezos and wants to use them to buy NFTs, they would need to have acquired the Tezos either by purchasing them on an exchange, or by receiving staking rewards from a Tezos staking platform. Once they have acquired the Tezos, they can then use them to purchase NFTs on a marketplace or exchange that supports the trading of NFTs. Depending on the marketplace or exchange, they may also be able to use other forms of payment such as credit cards, bank transfers, or cryptocurrency.

he could get that tezos only by buying it or getting staking rewards on it (or transferred by someone who used either of two) I intentionally put profits from any other activity out of equation since their origin is likely same)