The idea that these people are just sheep blinded by marketing is ludicrous. You might spend $5 on a beer instead of $4 because of marketing. You buy a $60,000 new vehicle over a $15,000 used one because it's a good product that you actually want.
I'm not going to debate that the Ford F150 dominates new vehicle sales in north America, but that's only accounting for the preferences of people who are buying new vehicles and doesn't track what the used market would buy if given unlimited options.
As for the marketing argument, there's plenty of discourse surrounding it. Most new pickups are sold with short beds and extra features which make them impractical for use by many commercial trades that do use pickup trucks. There's a question of whether the F150s popularity is because of the truck's utility or because of the aesthetic desires of purchasers.
visit tokyo, paris or any other transit oriented city and see for yourself