I mean, intercepting private business communications about say, factory openings or closings, would put the people with that information in a position to make large amounts of money by buying or selling property in those areas. There are dozens of similar examples that don't require much imagination to envisage. Blackmail material on politicians, insider knowledge on energy transactions and plans, advance warning on populist protests against EU policies, etc.

Just look at the history of any mass surveillance state to see how that works out in practice. The East German STASI is a relevant example, and there are others one could think of as well. Recommended watching: "The Lives of Others".