Yes and no. I have 18000 searches in my history, so I agree that you can't easily go through them all and trace out my life. And yet it is very simple to search it for trends, key events, or even pick a day and see what was going on then. I can do that, and Google can certainly do that (algorithmically of course). Now, I don't have a problem with that (and I value the ability to look back through my own life), but it does represent a trove of personal information.