Earlier quoted context omitted.
No, they can't 'sue' you; they can make a complaint to their data authority who will then decide if and what to do about it. So if your site blocks EU IPs and you then violate the privacy of someone in the EU grossly enough to warrant the data authority to make a case out of it, then yes. (provided everything else also applies, e.g. the things being talked about in the rest of this thread).
Put it in your TOS that European users are forbidden from using your site, and then if they complain to a data authority press charges under the CFAA, and sue them for damages you incurred due to their violation. Then let the courts hash it out.
I've said this many times here already, but law is not a closed rule based decision tree. Intent matters, and laws are written in a way that they can be interpreted so that their meaning can be adapted to new circumstances or different times. Now, I'm not going to argue about whether that's how it should be (because that's such a trite 1L discussion), but it's a fact that it is.
So no, that's not how it works.