Same with all those car and watch ads in magazines. It's not like regular people are constantly looking to buy a new car. But the brand must be etched into brains. Your neighbor must be reasonably convinced that people around him are on the same page regarding the prestige of a certain brand, else it's not worth spending on. So even if you can't afford whatever car model, the fact that you're aware that it's prestigious is already worth it.

This is somewhat weaker in personalized online ads because your neighbor can't know what ads you saw. Billboards and super bowl ads a much better for establishing common knowledge, but perhaps that's why influencer-based marketing is gaining ground. All followers know that all followers saw the embedded ad. Maybe they should introduce ads where it says "Your friend Joe Schmo watched the following ad:"