Why do you think self-driving cars are questionable? Maybe I've missed something, but it seems very plausible to me that they will take off; and even if Google didn't profit directly from the cars, their core business would profit from people having more free time to stare at a screen.

Many people are on the complete opposite side of the spectrum. I personally believe that autonomous vehicles are undoubtedly the future. They'll save an enormous amount of lives, allow new businesses to be created, eliminate the need for a drivers license (bye DMV), reduce insurance costs, and allow people to work, socialize, and actually have meals in vehicles (can turn the seats around and put a table in the middle). There are probably dozens of advantages that I missed in this post, but I don't see any reason to not aggressively pursue this technology.