They claim to be flat earthers on Twitter. Some portion are Poes (from https://www.dictionary.com/e/slang/poes-law/) but some seem to be genuine, and very determined not to see reality. Some are scammers who know, but are busy fleecing the rubes and don't want anyone to kill the golden goose.
The problem is how it's used as a conduit for plugging people into the anti-vax, anti-jew, anti-science, anti-reality club.