You can't. But Google is an ad company and an ad company does not just give away their most valuable resource, the data. So it's more about the devil you know then the devil you don't know.
An ad company can sold your data in various forms and formats. Maybe it won't sell your raw data, but will sell you nevertheless.
Even if it doesn't sell your data, it can use your data to make their ads more efficient for you and people similar to you. While that's their business model, they are borderline abusing you in the process. This not something I'm comfortable with.
They sell recordings of your activity for money, and you don't even get a cut. No royalties, no nothing. So they are profiting from your actions, without paying you. Bit unethical right? I generally consider my time valuable enough to sell it, and my actions even more so.
> and an ad company does not just give away their most valuable resource
Correct. They sell it for money. How exactly is that better at keeping your private data private? Google's power doesn't reside in the fact that it keeps your data private but in the fact that they have a constant flow of up to date data. When you hand over data to a company whose revenue (also) officially comes from monetizing it your privacy is forfeited.
Even if it doesn't sell your data, it can use your data to make their ads more efficient for you and people similar to you. While that's their business model, they are borderline abusing you in the process. This not something I'm comfortable with.