I had several discussions like that and always said something along the lines of: "Well, I am not so sure about it being a bad decision in the long term. I think time will tell." and every time people have valid arguments of why Brexit is bad for the UK, but still I will say something like "Lets see how it all turns out.", because we do not know the future.

When the EU cooks up the next surveillance law attempt, I am always reminded of those conversations. But where else to go, if even EU gets too crazy? There are probably only worse places with regards to privacy.