Propaganda works very well on smart people too. Here's how it often works: smart people like to be well informed. They drink a steady drip of "news" covering a wide range of topics. They therefore have a wide but shallow understanding of current events.

The topics are usually chosen for them (editor or algorithm). The news is packaged up for them to form an opinion at a glance (headline/social media post). They lack a deep understanding and so most things pass as largely believable, if at times a bit of a stretch. Topics they know deeply are almost always "covered poorly," but not the topics they don't know deeply.