"Studies show" that, once 10% of a population accepts a notion, it acquires a sturdy enough foothold to have a chance to widely penetrate the population. That's why cranky ideas and crazy notions - along with worthy notions - become part of popular culture.
Here's the report: Tipping points and beliefs – the 10% solution.
Politicians know this, which is why they are so full of BS. Their tactic is to repeat a meme until it's accepted by a quorum, even if you Maggie's Farmers know better. You can get 10% of people to believe that the moon is made of Roquefort, that vaccinations cause autism, that JFK's assassination was a conspiracy, or that the planet is about to burn up due to cars.