My take on Google X projects is to do cool things that may find alternate revenue streams to selling ads (or just do cool things, without necessarily having a business plan up front). Sure Google makes most of their money from ads, but they are trying lots of different things to make money elsewhere. Self driving cars, Ara, Google Glass, and others weren't trying to push ads, they were trying to find new products to make money in some other way (maybe).
Google's push to expand their Cloud offering is also showing them trying to pursue non-ad based revenue.
Google knowing where you go could make their models of you more valuable. Now they can specifically target ads based on where you go and when. Sitting in the cab waiting to get where you are going what are you going to do? Pull out your smart phone and see an ad offering a sale at a competitor to where you told the cab to go.
Google's push to expand their Cloud offering is also showing them trying to pursue non-ad based revenue.