Man, you're stupid if you think it's simply about them spying on you to see if you're breaking the law. Sure, they can use that stuff for blackmail at some point if you ever become a person of influence (i.e. politician, successful businessman, etc.). However, one of the main purpsoses behind data acquisition is similar to gathering data to predict the weather. Weather forecasts have become more accurate as the amount of data collected has increased. If there were a weather station every 10ft collecting information, then their forecasts would be extremely accurate.
Now transfer this idea over to predicting human behavior and you'll understand why all of this data collection is so important to them.