But if he does buy some thing, he's more likely to buy that company's version of that thing rather than some other company's version of it. So the adverts have worked on him.
A perfect example of how advertising works very well is branded generic over the counter medicine. It's exactly the same stuff, e.g. 200mg of ibuprofen is 200mg of ibuprofen, but people will pay many times as much for it
solely because of the name on the box and that's solely due to advertising.
An example:
https://www.wilko.com/en-uk/health-beauty/health-wellbeing/pain-relief/c/693?q=:relevance:type:Ibuprofen
Wilkinson's own brand 200mg ibuprofen caplets are 30p for 16.
Nurofen 200mg ibuprofen caplets are £2.50 for 16.
That's in the same shop, on the same shelves, right next to each other. Just a random example - I'm sure you've seen the same thing yourself for all sorts of things. I picked medicines because they're very tightly controlled so you can be sure they're identical.
When advertising allows a company to sell a product in direct competition to exactly the same product at less than 1/8th of the price, advertising clearly works very well.