Google is known for using a "Throw everything at the wall and see what sticks" approach in mobile technology. They have some successes like Nexus phones, Chromecast, and Chromebooks but they've also had plenty of failures like Google Buzz, Google Wave, and Nexus Q. They produce so many products simply because they have the money to do so and it pushes the market forward and causes other companies like Microsoft, Apple, Comcast and many others to step their game up. A great example of this is Google Fiber which is in only a few select markets, but its basically 1GB internet for the price your cable company charges for 30Mbps internet. Because of google fiber, companies like Comcast have doubled their internet speeds free of charge in order to fight back.
Now Google is trying to do it again with Project Fi. Rumors have been out for about 6 months or more that Google wanted to get into the mobile network
game, but no one really knew how they would do it. They announced on 22 April, 2015 exactly what they plan to do.