Hypothetical scenario: I am an advertiser and I want your personal data. How much cold hard cash would I have to offer you for you to willingly give it to me?
That's kind of a weak answer. The data 's privacy might be worth much more to you than i the data itself is worth to the advertiser. Remember the advertiser won't keep it private after they get it.
I'd make my data into a monthly subscription, 599.99$/month and I'd have a 20 page long "ECLA (End company license agreement)" that describes precisely where and how they're allowed to use my data.
If we're talking passwords, that's a no. If we're talking enough personal data that you could use it for spear phishing, identity theft or targetted malvertising, that's a no.
Honestly, no matter how innocous the information you want is, I would be extremely suspicious why you'd want it. And I'm certainly not turning off my ad blocker either.
Most people will never question Google or Meta's data harvesting while using their apps, but I'm sure you know this already.
The issue with offering me money directly for personal information is that I'd immediately nope away because that sounds like a scam or something malicious.
The real answer is close to free, provide people justification for giving you that data, and a little bit of barrier to entry to something they're already mentally invested in. And they'll give up their data. They shouldn't but they do
"Personal data" is something very abstract and most people have little to no idea what it means to give it away. Nowadays it's getting harder and harder to limit what's being shared so even those that have a vague understanding of what it means may not care too much.
I don't have social media accounts and I've been using VPNs nonstop for the last 10 years. Degoogled, Firefox, uBlock Origin, PiHole, etc. I got used to this, but it's a balancing act. I don't self host. I'm forced to use Windows at work. Credit card for groceries and stuff.
It's incredibly weird to think how easy it is to create a behavior profile of the average joe. It's unsettling to imagine companies like Meta and Google have decade's worth of data on people.
As you said, they shouldn't share that, but they do. And in places with no way to have that data "erased", some people will have an unfathomable amount of information about them harvested throughout their whole life.
Even if that data is never used for anything malicious, it's still disturbing.
Try this: first, give me (mere offers are refused). the cold hard cash. This experiment will cost you, oh, $1000. Cash in advance. Per hour. Second: see what you get.