Regardless of what you might think of Snowden, he has a good quip on this: "Arguing that you don't care about the right to privacy because you have nothing to hide is no different than saying you don't care about free speech because you have nothing to say."

Also, I invite anyone who thinks they have "nothing to hide" to put a publicly accessible webcam in their home bathroom. Everyone has things they'd prefer to hide, and that doesn't imply anything nefarious is going on.

I wonder if the point might be better made as "things you'd prefer not to share" - e.g. I don't think of myself as "hiding" when I'm in the bathroom.

You have nothing to hide from the current government (maybe). You don't know who will be in charge in 1, 10, 50 years. You might not need an Ahnenpaß right now, but do you really want evidence on record that will deny you one in 20 years time?

And the people buying your data could be criminals

"I don't have anything to hide."

"Domestic abuse victims do. Or do you want their psycho ex's to find them and kill them?"

Alternatively, “I don’t have anything to hide.”

“I’m sure it was the same for people who wanted to get an abortion before Roe v Wade was overturned.”

Not very effective, IMHO. All that's going to do is get you into an argument about Roe v Wade.