Does anyone have thoughts about what France and other countries can do at a policy-level to reduce such a attacks? Obviously, people should be more private with regard to their finances and hobbies. But what can governments do? 

I think the mods have let this thread continue because this topic is important. So to the small number of "thread-complainers": ignore this thread or contribute meaningfully by adding what, if anything, you think governments can do.

Again, what can governments do? This is not merely an issue for individuals to consider. It's a society-wide problem, too.