Vegans (I don't think it's healthy for everyone, but I have respect, even though some vegans are really annoying)
Doomsday preppers (I understand, but it doesn't work)
Anti-Vaxxers (the big problem is corporate profits, the main reasons for it are economic, there should be more focus on degenerated health due to processed foods)
Astrology believers (harmless, but silly at times)
UFO believers (lots of crazy nonsense out there, but so many serious people have seen them, I've heard personal stories)
Moon landing denialists (I quite like this conspiracy theory, even though I don't subscribe to it)
Young Earth Creationists (religious people can be annoying in general, but this stuff makes them really annoying)
Flat earthers (I've watched some videos on YouTube after a friend sent a link, these guys are super annoying, they have an explanation for everything!)
Climate change denialists (these are the worst, because people are going to die and suffer because of their actions, + they're old and white and have been completely brainwashed by last century's Cold War propaganda)
Can you add '
scientism supporters' as well? I'd probably put those people between Young Earth Creationsts and Flat Earthers.