>Because they're convinced that because they have nothing to hide, the law will never turn against them.
Yeah, this is a tough one to counter for me. Trying to identify a specific thing they do that may become of interest to a specific abuse of law enforcement.
The Jews in Amsterdam had nothing to hide ... until they did.
Do you give everybody your tax returns? No? Then you have something to hide.
Do you give everybody your phone records? No? Then you have something to hide.
Do you give everybody your web history? No? Then you have something to hide.
etc.
I mean, one thing you can look at is news stories about the police grabbing the wrong person, trying to find someone who's as much like them as possible - but any example can be rationalized away.