You admit that there is a risk, but what can you gain from taking that risk? Because without gain, what incentive to you have to take the risk? Yes, I agree tha

You admit that there is a risk, but what can you gain from taking that risk? Because without gain, what incentive to you have to take the risk? Yes, I agree that the likely outcome isn't that bad if they break my trust but only tracking my search queries would be quite revealing and sensitive and would reveal stuff that I tell very few people. So, the thing that yahoo did (releasing all queries with an "anonymous" user ID) could have had huge implications for me personally. In terms of friendship etc. the gains are huge, but what about google? Relevant ads? I have never, ever, in my life clicked on a google ad on purpose (probably a few by mistake (thus I immediately left the page)). And that despite that they are "relevant", so... What can I gain from letting google collect all that information about me? And honestly I believe you get much better ads by targeting a site rather than a person. The best ads and the only ads I've ever positively responded to are those from a local tech site (the same ads but on a food site would probably not interest me as much).