I've thought about this quite a bit. I'm extremely technical, have a background in marketing and publishing, and so I'd be a big liar if I said that ad tech has never appealed to me.
My time in marketing and publishing make me look at this differently. 20% is a lot of traffic, but behaviourally, they're different enough to make me question the investment.
With most people, the worst case scenario is they'll ignore an ad. So few are bothered enough to even find the content of some ads objectionable. If someone goes to the trouble of using an ad blocker, there's a probability they will be actively hostile to the ad. This hostility would hurt both the brand advertising and the publisher.
Then, I think through liability. If my ads serve malware, that's bad. If I have an anti-ad blocker and serve malware, I could be fucked. Any ad network is attractive as a malware vector. One that defeats ad blockers would be too juicy to ignore.
As a publisher, I wouldn't pay to block ad blockers for display ads. The risk would be too great. I would possibly pay per click, but only an extremely reduced amount.
The risk of doing damage to my brand would exceed any benefits of advertising to a hostile persona. You'd have to offer the service at an extreme discount to even have a chance. And honestly, even then, I doubt that I'd trust you.
It's pretty easy to stop ad blockers, but it's next to impossible to predict the potential damage. Marketing has to be as much about risk aversion as about opportunity maximization.