Conspiracy theories and pseudoscience focus on theories that can't be tested. Real science focuses on theories that can.
If one scientist thinks the moon is made of cheese, that's a hypothesis. NASA can test it by sending up a probe for a sample. It returns with moon dirt, so this guy says, "Okay, but that one crater is probably cheese." Another probe, more dirt. Now, he says, "Okay, but I bet the moon's core is cheese." Not only does NASA not have the tools to test this, they are no longer willing to humor a hypothesis that is more and more unlikely.
NASA criticizes him for spreading pseudoscience. He uses the criticism as further proof of NASA trying to silence the truth.
He has no proof of the moon's cheese core, and NASA would have to spend a huge amount of money and effort to disprove his theory -- BUT WAIT. He's already made NASA the badguy, so even if they got a piece of the moon's core, this guy can wave it away as fake. His followers no longer trust NASA to tell them the truth. They only trust this one guy. And anyone who listens to NASA over this one guy Is Part Of The Conspiracy.
Meanwhile, real scientists tested the moon dirt from the first two probes and hypothesized that underneath that was probably more moon dirt and that the core was core-like (I dunno what the moon's core is thought to be like, but like that, that's what they think). They do not think "it's cheese" because the evidence so far suggests otherwise. The real scientists don't worry about a cheese core. They test the theories they can test, and they gather information in order to learn more about the moon, and maybe some day they'll sample the core, but not today, and definitely not because a former colleague turned conspiracy theorist insists it's cheese.
There are conspiracy theories about vaccines, Covid, the government, aliens, etc. They rely on people believing only the conspiracy theorist and no one else. They undermine trust in experts, organizations, and authorities so that even when their wild theory is proven wrong, proof that the theory is wrong is written off as another attempt to silence the "real truth." It's impossible to disprove because they don't GET their followers with proof. Instead, they get people to buy into the belief that the experts and authorities are liars and villains, isolating individuals from the very people doing the real science that disproves the conspiracy theories.
It's insidious, and this is exactly why I'm not okay with conspiracy theories at all ever.
pseudoscience (n.) a collection of beliefs or practices mistakenly regarded as being based on scientific method.
conspiracy theory (n.) a belief that some covert but influential organization is responsible for a circumstance or event.
