Here's that special word, "FREE." Thanks to Jim Hays for the following info: "Google now offers downloads of its Google Earth Pro for Windows and Mac for free at: http://www.google.com/earth/explore/products/desktop.html. "Google Earth Pro is described as a '3D interactive globe that can be used to aid planning, analysis and decision making.' It's also an effective way to traverse the globe without leaving your house."
John Carter noted that on of 3-25-2016, the Mac download of Google Earth Pro did not validate when attempting to install the package. This does not mean it won't work for you, so keep trying. In addition, the app is totally free to everyone now. So says the website.