[danpalmer]

I don't really understand the basis for this comment/thought. I know it's a fairly common one, but I just don't think it tracks reality in any way.

Google has a reputation for taking in a lot of data about user behaviour for targeting ads. That's pretty well defined data though, from well-defined sources, with well-defined semantics. Things like page views.

How would Google ever be able to "hover up all your data" and get any benefit from it? What is the data? Where did it come from? What are the semantics? How are users identified? How is that mapped to users Google knows about?

It's just entirely impractical to do anything with it, and that's leaving aside the fact that I imagine it would violate the terms of service, the contracts Google may have with businesses, and may constitute a significant legal issue with regards to data misuse.

How exactly do you imagine that Google could do this, and what exactly would their motivation be to do so?

Mandatory disclaimer: I work at Google, but not on any of the above and I only just started. My feelings on this are only informed by my previous time as a customer of Google Cloud.