As has been stated over and over again -
AdSense Total Acquisition Costs (TAC) averages 60% of AdSense partner revenue (more for some, less for others).
Google gets $10B revenue from AdSense, and pays out $6B to AdSense Partners as TAC. This results in $4B profit for Google from AdSense operations - NOT less than $1B, as shown on the chart!
However, this is STILL far less than the income Google receives by displaying ads on its search pages, so the basic point remains valid. Google COULD cancel AdSense at any time, and their bottom line would not suffer that much. I'm sure this fact is disturbing to AdSense publishers, such as myself.
If Google ever gets tired of the web "cesspool" (as defined by their CEO), they could say good-bye to AdSense. It is AdSense that is the primary cause of the cesspoool, by creating millions of websites that consist of stolen content, and jibberish content created by non-English speakers. Everybody wants a piece of the action, and tons of cr@p content gets created. If AdSense were elimated, millions of cr@p websites would disappear overnight.
Google is already cracking down on India and Pakistan for creating much of this undesired content. One of the biggest reasons for this is that Google does not support Urdu, the language of Pakistan, and Google does not support Hindi, Bengali, Punjabi, Telugu or Tamil, the primary languages of India. So we get thousands of India and Pakistan webmasters creating less-than-ideal webpages in English.
[edited by: Sally_Stitts at 5:30 pm (utc) on Feb 25, 2010]