Harm is great, now is about the era of big data, as long as you get enough data, you can analyze all your information, read your call records to know your real name, contacts your interpersonal relationships, you have published any speech, social networks on the interpersonal relationships, read your geographic location, determine your nearby people, stores, stations, public **** facilities, and then analyze the tracking of your activities in the vicinity of the behavior, everything is hidden. Activity behavior in the vicinity, everything is nothing to hide, it can be said that as long as you give them a few key points of information, then you can deduce all the relevant information about you, your family, friends, bank card, address, work unit, car, house ---------- all! Big data era everything has nothing to hide