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.