Hi Detlev, it is scary isn't it. But it's not only Google.
Even Apple, Nokia and many other collect you data.
During the last days I found a project that does a bit for your privacy at home.
It is called "pi-hole" link to pi-hole!.

This is an overview of the last 24 hours of my local internet traffic :

As you might see nearly 20% of it was blocked.
All you need is a raspberry pi and half an hour to setup.