Because it's not just the ADs. For getting good targeted ads, you need to know a lot about targets. And that knowledge can be used for other things than just s

Because it's not just the ADs. For getting good targeted ads, you need to know a lot about targets. And that knowledge can be used for other things than just selling ads. It can be used by politicians to target specific groups, it can be used by scam artist to get access to more susceptible people. It can be used by business, like payday loans, cc companies, lotteries, etc. to target people that are in already bad place, to dig a hole even deeper (and that already happens today). It can be used to target people who are whales in one microtransaction whatever, to spend on some other etc. It can be used by bad governments to target people with specific viewpoints, smear campaigns, find dissidents etc. They all need same kind of data. And even if you collect that data for one purpose today, doesn't mean it cant be used for something else in 10 years time. Just because Google might not sell that data right now, doesn't mean it wont in the future. I would have a lot less problems it it was just ads, but it's really not.