Only about 30–50% of people use ad blockers. The average person is a lot less technically savvy than you realise.
I'm sure anybody would find it just as weird after they experienced an ad blocker for a short while, they just lack that initial impulse or idea that it's possible.
3-5% perhaps.
"Chrome is used by 3.45 billion internet users. That's up from 2.74 billion in 2019. Chrome has a worldwide browser market share of 63.87%."
https://backlinko.com/chrome-users
"Over 30 million Google Chrome users use uBlock Origin"
Source: the very article.
Even in the Google Chrome "niche", does 30 million out of 3.45 billion sound like 30-50% to you?
The overwhelmingly vast majority of human beings using web browsers are not using ad blockers. They wouldn't know how and it wouldn't occur to them in the first place.