What do you mean are they a thing? yes, they do exist. Most of it is enabling money laundering. Lots of people have made a lot of money from them however you need a decent amount of cash to get started with getting an NFT.
I don't get why people choose to buy NFTs at all. What's going to distinguish a screenshot from the "original". Technically, even the original is a copy of the actual original when it was uploaded online.