Every once in a while I run across something like an adblock blocker. I scroll up to the top of my browser and click the button that disables java script, reload the page and the world is green again.
Unless you have something that is absolutely unique, most users will simply look for another site that has the information they seek. Then you lose the user and a possible sale of ad click.
Something more important. There is an easily findable article that shows that clicks on ads is down and that also text based ads are the most frequently clicked. Text ads are generally carried by the server/webpage where as the PPC ads are carried by ad servers.