The high prices are a known gimmick for grabbing headlines. “Useless NFT sells for $100,000” is (or was) a sure-fire way to get your NFT into the headlines. The trick was that you could actually bootstrap these high prices yourself without actually spending the money. If you have $100,000 in ETH sitting around, you didn’t have much to lose by using it to “buy” an NFT from yourself in a transaction with yourself.

Sounds like the problem is how these transactions escape any sales tax, thus these gimmicks and other forms of money laundering simply have zero cost or oversight.