alt Hacker News> Every dollar you spend on advertising provides additional customers.
If you’re just taking these customers from competitors, the marginal utility can be pretty low.
e.g. If you consider a world where there are no ads for cars, people aren’t going to meaningfully lose out of the utility they get from cars, carmakers simply avoid the prisoner’s dilemma of having to advertise as much as the next manufacturer.
The world isn't zero sum, advertising grows the pie for all involved. One of the best examples would be the iphone when it was released. Even in your example category of cars Tesla and later Rivian/Lucid/BYD marketing was a game changer for electric vehicles.
Very few ads are for products where exact 1:1 competitors exist (though it's nonzero, maybe something like a commingled Amazon Basics widget).