I interpreted the comment to mean something more like the derivatives market. In the derivatives market, you start getting "weird" stuff like futures contracts, collateralized debt obligations, or credit default swaps. Last two examples are, admittedly, a biased reference to 2008 since those are sort of the poster-boys of that market crash. Futures contracts aren't really that weird, but certainly more weird than just owning stock in a company.
So people might be trading (as in 2008) to "own" some N-th power representation of private debt that ends up going to zero because the underlying private debt itself was not sustainable. It's different from NFT, but for each degree of distance the financial instrument moves away from the real world, it looks increasingly weird, e.g. I own a share of insurance on a fraction of a bucket of debt people took out to buy their homes. (And I still think this is better than NFT unless the NFT has some underlying real-world thing tied to it.)
Derivatives markets always have some claim to an underlying financial good. If you buy futures, you can redeem it later for the good the futures guarantees. NFTs have zero relation to the underlying asset they are being connected to. All you're buying is a pointer to a piece of art.
So people might be trading (as in 2008) to "own" some N-th power representation of private debt that ends up going to zero because the underlying private debt itself was not sustainable. It's different from NFT, but for each degree of distance the financial instrument moves away from the real world, it looks increasingly weird, e.g. I own a share of insurance on a fraction of a bucket of debt people took out to buy their homes. (And I still think this is better than NFT unless the NFT has some underlying real-world thing tied to it.)