Specific examples of the value to a business is when companies like Netflix and Hulu increase customer satisfaction and retention by analyzing

Specific examples of the value to a business is when companies like Netflix and Hulu increase customer satisfaction and retention by analyzing massive amounts of data in real time to suggest shows they might want to watch based on thousands of other users and many other data points.

Because of current events, this is a big security concern. What is the problem with this technology?