How many users can I reach with Google Display AdSense?

According to Google itself, theoretically it is possible to reach 90% of internet users through a network of 2 million websites using Adsense. These numbers seem a bit inflated, but even if they were respectively 45% of users and 1 million websites, it would already be quite enough. The real problem is not how many people you reach, but what you tell them once you’ve reached them.