Nft's can't really be copied but those who try to are just imitations or fake and can be easily spotted and reported.
But you can make another one that just resembles it, and start selling the hype.
Because kitties or apes, monkeys or stones, they had no intrinsic value at the start other than hype, it's not like you hand one to some guy and tell him this is the only copy of the Michelangelo's David, and nobody will be able to sell a different one with the other arm raised up or one that is more yellowish or anything else.
NFTs have this problem, the public doesn't care about this being the first monkey smoking a cigar NFT nor does it care that two days later there are 1000 collections of nearly the same monkey smoking pot, it's just a fad because everything can be replicated with another fad!
After all, some people put their whole time of their lives in videogames, sometimes taking years until reaching determined achievements and being able to acquire some valuable items in-game. Nothing fairest than letting these people make real income from it.
They can do it right now without altering the game at all, without any kind of NFTs, and second, the have the cake and eat it and sell it stuff doesn't work, the money that this guy is getting paid has to come from somebody, and the moment the balance is broken a more ask for a payment, well....you end like Axies!