Many people spend 10% of their waking lives in cars, and more of it earning money to afford their cars. Automatic driving with the associated ease of fractional car ownership is potentially huge. Keep in mind that not everyone works at a desk job that can almost as easily be done remotely.

Social networks really, really aren't nearly as impactful in the the productive sense. They've mostly made it easier to chat with more people, and browse through more photos - things that are intensely interesting to people, but not really useful.