Paid stream media
A bunch of jerks, a company, or a lonely weirdo who uses big news channels to make up fake facts so people think it's real. Just keep lying and yelling it loud enough, and everyone will believe you're sane.
A company says everyone is rich, but they're just lying to get you to buy their stuff.
A news channel says the sky is falling, but it's just a paid ad.
A politician says the moon is made of cheese, and now everyone believes it.