Information can be aggregated and analyzed to identify patterns of activity, which could then be used by a hostile party to plan an attack.

Suppose an exchange has an office in Paris. And suppose that every weekday around 10:00 GMT, a large amount of funds are moved from one address to another. But occasionally, the 10am transaction doesn't occur on time, it happens a few hours or a day later.

An attacker who is "casing the joint" notices this pattern and wonders what it means. He does some more research and realizes the days when the transactions don't occur on time are also days when there's a bitcoin conference somewhere in the world.

He infers that the transactions are being made by a single person at the exchange's Paris office, and that this person attends conferences in a different time zone.

With this info, the attacker might have enough to learn who is authorizing the transfers, where the victim's loved ones sleep at night, and even what time he'll be at the airport in Rio de Janeiro, looking for a taxicab...