They don't bother (yet). As long as they know only tech geeks are attempting this custom DNS config, and those tech geeks are unlikely to click on ads, they don

They don't bother (yet). As long as they know only tech geeks are attempting this custom DNS config, and those tech geeks are unlikely to click on ads, they don't bother going the next step. Now, if Pi-hole or similar suddenly becomes mainstream, that'd be a different story.