Propagandists spend so much time and money on propaganda

Your mistake is believing that they are spending much money. It's actually a small fraction of the money they make from burning the planet, miniscule if compared to the amounts accumulated over decades, and it's also the easiest option. They could also just buy politicians who are incredible cheap but still more expensive than the ongoing media desinformation campaign that mostly runs on its own because the clickbait industry journalism has become runs on stories the propaganda victims want to hear.