What does Google gain from Google Earth and Street View?

They continue to spend millions mapping every major city and town on Earth. What is their ultimate goal? How is it financially viable?What does Google gain from Google Earth and Street View?
Google Earth will attract people to visit Google's website and that brings popularity and money to Google Inc. And there is a Google Earth Pro that must be purchased to be downloaded; that too, benefits Google and without Google Earth, people would not have a "feel" of what is like to use Google Earth. Google Inc. is growing bigger and bigger, now that is working on a Google Tablet and Google OS, and more to come, such as the Google TV.What does Google gain from Google Earth and Street View?
They gain with location based marketing.What does Google gain from Google Earth and Street View?
If people view their maps, they're coming to their site, and they'll be more likely to use their other services.