Specifically, I am interested in tangible examples.
The one thing I got from your post is: Meta can target you to deliver better ads.
If you have other specific examples of what else can happen, please elaborate. I am curious
Ok, a specific example: by a weird twist of fate, my country outlawed abortion (in most cases). Currently it's easy for affected women to travel somewhere and get help. Some people don't like it. With widespread tracking, it will be possible to target and punish women for breaking the law by getting abortion.
I can see that happening in the future albeit with a low probability in the Western World at least. Of course you never know
Western democracy doesn't help much when a higher up wants to get you.
And then there are all the crazy bastards beating up people for their religion or their sexual orientation. It's been shown that Facebook leaks some personal data to advertisers with carefully crafted campaigns.
And if that doesn't worry you, there's also all the fraud that is spread via Facebook ads: "Better Ads" means "More convincing cons". Con men use ad targeting to deliver exactly the kind of fraud you are most likely to fall for. A relative of mine fell for a finance scam -- it seemed perfectly legit, and thanks to Facebooks accurate targeting the campaign was delivered exactly to the right person that would fall for it.
Don't give them your data.
I want no ads in my life, ever.
When I need to buy something I look for research, reviews, competition, people who actually used the thing for some time and comment on the thing's weaknesses.
I want to control when I start being interested in something, and when I stop also.
When I need to buy something I need knowledge (weaknesses) and control. Advertisements are exactly the opposite of that.
So... no ad can ever be a good ad for me. Period.