Highly disagree. I can do it with 3-5k visitors a day. (Assuming they are USA visitors)
Maybe in the warez scene it works like this because there aren't premium ad networks whom will accept a warez site.
Some people can do it with even less than that,It just depends what method you are using. CPC,CPM or CPA.
It really depends on which ad network your using if you run a site and how many hits your site gets a month. Now if your using surveys you have about a 60/40 chance on making good $$$ with surveys since most people hate them and pass on the every time. If your a uploader using paying file and image host and spam 50 porn forums with a auto poster you will make decent money. If your posting good content and as long is the file host is paying