They are having data about themselves collected without their consent. That is the harm.
Drink driving is bad.
Why is that?
You might cause a crash.
Why is that bad?
People could die.
Why is that bad?
They'll be dead.
Why is that bad.
They don't get to exist any more.
Articulate your reasoning!!!!
- Who is likely to vote Bernie?
- Who is gay?
- Who is gay, but not out?
- Who is cheating on their wife?
Etc etc..
If you can't see the potential for harm at both the individual level (think extortion) or political level of that kind of power I'm not sure what would convince you.
That's plenty harm enough all by itself.