I thought it was still something stupid low like 10% of people using adblockers?

More than 10% of telemetry-enabled Firefox users worldwide use adblockers. In Poland it's 15%. In the United States, Germany, and Russia it is closer to 20%, and in France it is closer to 30% [1].

[1]: https://data.firefox.com/dashboard/usage-behavior (see near the bottom of the page)

But Firefox is under 5% of browser market share (generous estimates still seem to put it under 5%—the low-side estimate is closer to 2.5%) and its users are almost-certainly far more likely than most to use ad blockers.

Not in Germany

You're arguing against a straw man.

I don’t follow.

“Not a lot of people use ad blockers”

“quite a few telemetry enabled Firefox users do”

“but Firefox users are a tiny share of total users and probably way more likely to ad block than most web users”

Where’s the straw man?

Do you see how you used the word “probably” to signify that the thing you’re claiming is just your opinion and not based on fact?

It’s a fact that it’s probable.

Do you want to pretend-argue with me, or to positively assert that Edge, Chrome, and Safari users ad block at a rate similar to Firefox users? This is silly.

Also, that’s not what a straw man is.

And the population that will block ads will include a lot that block telemetry as well on principle, so the percentage is higher than that.

But the population that blocks (opt-out) telemetry is likely low, at least that is what I would assume. So I don't think it makes a big impact

The ~20% using adblockers probably aren't a random cross section of society, but more tech-savvy audiences that advertisers will pay big $ to reach.

Most users have never even heard of Firefox. I just installed it on someone's phone yesterday, along with uBO; they had never heard of it before, but were very excited about being able to watch YouTube without ads. My social circle isn't very large, so me helping occasional non-technical users install FF+uBO on their phones isn't going to affect the numbers very much.

Even in the tech company I work in (not an adtech company), most people use Chrome, not Firefox.

Germany, mostly older users. We had a manual HEAD request to our google ads script for a while where we’d log the results (successful: yes/no). 30-35% blocked ads.

Statista has a pretty nice writeup available here. [1] Granted some of the data is going to be contradictory, because they are an aggregator and not a source. So for instance in one section they claim the overall rate of ad blocking in the US is 26.4%, yet in another section their data suggests 30% of mobile users are blocking ads, while 51% of desktop users are. Pretty hard to see how that adds up to 26.4% overall.

Regardless of the noise in the data, it at least seems clear that whatever the number is - it's way above 10%, and growing. This is probably why YouTube is willing to go to war with their users over it, one of the very few things Google has ever done that could directly imperil one of their monopolies. Potentially driving off a substantial number of your users at the time when there are more viable alternatives than ever is a quite a bold move. Let's see how it plays out.

[1] - https://www.statista.com/topics/3201/ad-blocking/#topicOverv...