Heres why: The whole idea of money being made in adsense revolves around the idea of someone clicking on an ad. This is where the money comes from in adsense. But lets take a closer look at it... When someone clicks an ad on your site - 3 people benifit: You Google The guy/gal who paid to have the traffic diverted to his site with the ad Here's the problem - there's 3 people in the equation, meaning that 3 different people benifit from the visitor clicking the ad. Therefore you're sharing the benifit with 2 other people. Now you've put in the work to get the visitor to your site, but once you've done this google makes money out of your hard work and so too does the guy who paid for the ad (not always but generally he does). Therefore the visitor who lands on your site is worth MORE than what you getting out of it becuase 2 outside entities are coming in and able to make a profit on it while at the same time leave you with some. This has always bothered me about adsense. It's not a good deal for the site owner.