> better said will target you with ads.
The difference between selling location data, and selling ad targeting, is the difference between actively stalking someone, and sending unsolicited spam to "Current resident" at "Every address in a city block".
What harm can I inflict to you, via targeted ads? Some. You can think of some creative ways to do so, but it's not a very effective way to inflict harm.
What harm can I inflict to you, via buying your location data? A hell of a lot.
If you don't trust Google to be a good steward of your data, that's one thing. But let's not conflate selling your data, with selling the ability to mass-advertise to a demographic that includes you.
Do you see how people have weaponized social media through data? Google ads might not have been used in a nefarious way just yet but that's likely because it hasn't been thought of.
What about someone showing you an untargeted ad? Where would that fit in?
[1] Or, if you prefer, a remarketing ad, instead. I have very little patience for those.
Remember how everyone got very hot and bothered about precisely this thing happening in a recent U.S. election?
If your problem is that advertising is used to manipulate public opinion - consider - why do we even allow political campaigns and paid speech? Its only purpose is to manipulate public opinion, and to trick stupid voters into voting for bad people.
I'm afraid your position is not entirely ideologically consistent with how we determine what kind of political speech is allowed, and is not allowed.
A while ago there were some fun articles about "how to prank your roommate by creating an audience of 1 and running creepily personalised adverts". What's the smallest demographic you can define on google?
As far as I know, advertisers never receive personal information from Google. Google hordes the personal information and shows advertisements (provided by the advertisers) to their users, using their personal information.
It would be rather contrary to their interests if they were to send their user's data to other parties. They'd lose their commercial leverage and their ad network would become less valuable.