French plans for massive surveillance to catch people with unexplained wealth carry a big danger of tyranny.

The talk of "data protection" is a clear example of how that concept is bullshit, The idea is that the state collects your personal data and uses it against you. So what if the state "protects" it against some other use against you?

Perhaps it is acceptable to look at at publicly visible postings for this. But the state is surely not going to limit itself to those. I expect it will also look at "private" communications on the same sites.

The danger of snooping on people's purchases on eBay is that once the state benefits from tracking people's every purchase, it will try to force people to identify themselves in every purchase.