It's undeniable that ads work. This has been endlessly researched for decades. Trust me, companies don't just throw away billions without spending millions to see if it is worthwhile.
My girlfriend works in the beauty industry on the product side. Even more important that having a good product, is having a good marketing campaign. Products live and die by their advertising. And believe it or not, lots of people click on ads.
Step back and evaluate the situation considering your thoughts on the whole population, people in general, not looking at it from your perspective with people you associate with.
Sometimes I think the ad market is just an emperors new clothes situation. Where really it doesn’t move the needle much but the implication it does is profitable and then both sides of the deal are incentivized in their own way to upkeep the Big Lie. The ad companies make their money collecting money from ad spend. The people in charge of ad spend justify their jobs by spending money in ads and showing comparable rates of ad spend among their competing companies in their industry. The investors prefer to see a company spending on ads like other comparable companies in the sector such as to not devalue its stock price.
But does it work? Ask anyone if ads work on them they say no. You have to get a psychologist to do some unreproducible study to prove that it works at all. And given the perverse incentives above, it just doesn’t matter if it works. The beast exists and that justifies itself.