The theory that miners are making spam transactions to drive the fees up has floated around since 2016, and it never really worked, because if you are mining your own spam transactions, you are losing more money than what you gain from driving the fees up.

There's a simple explanation - there's a lot of people who are crypto rich - early Bitcoin and altcoin investors who have millions worth of coins, and those people can easily play with those NFTs even if they lose money, because they are just that rich.