1. The advertisers who pay for it all still get their money from us, but baked into prices of the things we buy from them. There is no free lunch.
2. The overhead cost of advertising is huge and we pay for that too. Ad systems and data collection systems, ad engineers and people like the author. Ad agencies. Creative agencies. Ad tracking. Marketing departments.
3. We pay the opportunity cost of a product that cannot put users first because they live or die by giving advertisers what they want (what we want only indirectly and secondarily, if at all). This includes both the cost of lost privacy as well as well as design that optimizes advertising revenue. As has been said, we are more Google's products than we are their customers.
4. We pay the social costs. Democracy and the free market assume people make voting and purchasing decisions based on facts and reason. Advertising is predominantly about manipulation and deceit. To me this is the most expensive cost of all.
Added together, we are paying a lot more for "free" web content and services than if we could just straight up pay web sites for straight-up ad-free versions. A system to make that convenient is possible, but we're too hooked on ads to even try.
[This is a condensed version of a more detailed case with reference links that I made here: https://news.ycombinator.com/item?id=7485773]
"Everyone gets that advertising is what powers the internet, and that our favorite sites wouldn’t exist without it."
The author nails the two sources of the problem, that advertising drives the internet, and that everyone believes we have no choice.