"Take all of the prescribed medication" : "They're just greedy and want to make me buy more"
vs.
"Take all or you'll breed antibiotic-resistant bacteria that cannot be treated and you will die and kill the human race" : "I better follow this prescription"
It's from Friedrich Nietzsche's "Twilight of the Idols": "What does not kill me, makes me stronger."
Also, most people don't know that either. Today it's just a saying, that's been repeated by people for decades.
Both of them are wrong, btw. Pharma companies are greedy and they do everything they can to make you spend more. Doctors are influenced by them, often very subtly. That is a fact, not a conspiracy. But the fact also is, that doctors save lives and most have noble intentions (despite the meat grinder medical career is). One needs to learn what information belongs more to "greedy companies" category, and what belongs to "life saving science" category. It's no surprise people get confused about this - and that's why you absolutely need to explain to them why they need to finish antibiotics treatments.