> As a general market trend, why are click through rates decreasing?

Because the advertising industry has structurally educated users to try their hardest to ignore the ads, resulting in every more obnoxious ads, which are then even more forcefully ignored. And that in turn gave rise to adblockers, which are now more or less a requirement if you don't want to lose your sanity while browsing the web.

> which are now more or less a requirement if you don't want to lose your sanity while browsing the web

For a long time I wondered why people said this. I don't use ad blockers and didn't feel it was that bad.

Then 2 things made me understand. First, I pay for YouTube. If you don't and don't block their ads, they seriously test your patience as you browse. I tried it for less than an hour before I couldn't take it anymore.

The second was looking for torrents and hacks (it was for a legitimate and unambiguously legal purpose too, no gray area, but long story!). Those sites are literally impossible to use without ad blockers. Same thing for tools related to diagnosing PC issues. It's all ads over ads over scams and trying to get you to install some adware as you navigate the site trying to install the actually legitimate tools.

I very rarely do either of those things (YouTube without subscription, and navigating the "gray" web), so I never realized just how fucking awful it can get.

Hell, I'm a YouTube Premium subscriber and I still have an ad-skipper for all of the in-video promotions. It's not quite as bad as direct YouTube ads have gotten but it's still a noticeable change in itself.

I dont think you even need to consider gray web stuff. Your average news site is awful and unisable without an ad blocker.

It could be because of number of ads shown per query. As number of competing ads goes up CTR goes down.

I'd also like to see a source for that claim. Been working in digital advertising for 10 years, so I'd be seriously interested. We've changed so much in our advertising over the years I wouldn't be able to tell whether that trend really exists.

There seem to be some logical considerations that make the growth of advertising self destructive for advertisers. The big one is that the more ads one sees, the less likely they become to interact with any given ad. There will also likely be an increased ability of users to ignore the ads they do see. As advertisers see returns from advertising decrease, the costs for advertising will gradually trend downwards. This will enable even more advertisers to start advertising.

It's almost like a sort of reverse network effect. The bigger you get, the less desirable your product becomes. And the advertising industry's getting quite large.

Also there are more "branding" ads which are placed just to get the company's logo in your face and don't necessarily need a click to do their job.

If I want to advertise my new Windex(tm) flavored Mountain Dew[1] then all I need is people to see it. They're not likely to buy it from a click, but I want them to remember it next time they are at the grocery store, and I'll pay to shove it in their browser.

[1] Not currently available in retail stores

I personally just open a new tab and search for the same (i wonder if google can connect those 2 dots to count it as conversion)