I suspect there are two parts: some of these (drones, fiber) are intended to provide a more seamless Internet experience to more people. By extension, it means more advertising.

Others are investigations of revenue streams beyond advertising but able to leverage Google's in-house strengths in machine learning, computer vision, distributed systems, AI, and other related topics. This is not strange given Google has had subscription based services for some time now: e.g., Apps and Cloud Platform.