The content creator gets paid by the ad company for showing you the ad, the ad company gets paid if you click on it.
With that in mind, there is a net-positive outcome for the ad-company if users who aren't going to click on the ads use ad-block, because that means they don't have to pay the content creator for showing ads that nobody clicked on. They only miss possible profit if you're using ad-block but would have clicked on an ad were it presented to you, which is unlikely considering ad-block is generally opt-in. Depending on the ratio of how much they make per-click vs. how much they pay the content-creator per ad, they could definitely come-out with more money due to users using ad-block and not requiring them to pay the content creator when they wouldn't have clicked on the ad anyway.
Not all ads are click based. You're thinking primarily of AdSense and a lot of retargeting ads but most ads are still bought on a CPM basis based on views. Yes, if a publisher consistently shows ads that have a low CTR (clickthrough rate), then the ad network should optimize out of displaying that ad on that site.
With that in mind, there is a net-positive outcome for the ad-company if users who aren't going to click on the ads use ad-block, because that means they don't have to pay the content creator for showing ads that nobody clicked on. They only miss possible profit if you're using ad-block but would have clicked on an ad were it presented to you, which is unlikely considering ad-block is generally opt-in. Depending on the ratio of how much they make per-click vs. how much they pay the content-creator per ad, they could definitely come-out with more money due to users using ad-block and not requiring them to pay the content creator when they wouldn't have clicked on the ad anyway.