Interesting in this context is completely divorced from morally good/bad. Could be any group from any area at any time in history. I’ll start with a few, followers of the cult of pythagoras, contemporary black Hebrew Israelites, antiracist skinheads and the Amish (neo-luddites in general). Don’t be racist or a prick to other people discussing.
Space deniers.
They are a sub-set of flat earthers. Not all flat earthers are space deniers, but every space denier I’ve seen is a flat earther.
Some of the more prominent ones like Level Earth Observer spend innumerable hours picking apart International Space Station live footage as “fake”. Things like space rocket launches need to be picked apart to absurd degrees as well. Every camera glitch, every stutter, every little movement is hyper-analyzed and declared to be a fraud.
I find it all fascinating. Some of these deniers put forth their own lay theories, which are usually very Biblical in bent, but many of them like LEO will twist themselves into incoherent knots refusing to admit they have a viewpoint and that they are “just asking questions” despite pushing back in a very particular way to all the answers they get.
Some of them like “CC from New York, Westchester County” are just totally off the deep end, not even playing word games, just conspiratorially ranting without even internal consistency.
I’ve only ever interacted with a space denier directly once and it was as equally interesting as it was frustrating.
There’s a big flat earth/space denier overlap with other fringe ideas like young earth creationism which gets you into Kent Hovind territory. That’s interesting in its own way but also full of slime.