Say, you have a bunch of money made from selling cocaine and you want to buy a house. It's really hard, because people will want to know how you made the money without a job. So you buy some NFT for about 10k with your clean money. Two months later, you sell the NFT for 500k to an anonymous buyer online, who pays through crypto. The buyer is you, buy nobody knows that, because they're anonymous.
You now have 500k cash, you will need to pay some taxes over your gains, but then the money is clean and when you buy the house you say you got the money through an investment in NFT.
Meanwhile, some random people read about how you made 10k into 500k in two months by trading NFT. So people will start investing in it, making your money laundering less obvious.
This is a bit of a simplification of what could be happening, but it does seem feasible.
Bonus points, as now a lot of people think the NFT that my dirty hand still holds is worth $1m!
That's the purpose of money laundering - to bring ill-gotten gains into the light so they can be used.