One consequence is that your personal data gets sold to whoever wants to pay for it. In the long run a serious consequence will be that all the data they collec

One consequence is that your personal data gets sold to whoever wants to pay for it. In the long run a serious consequence will be that all the data they collect could be used by a dictatorship to suppress opposition. I am sure Hitler and Stalin would have been very happy with the data Google and Facebook have. Once you have full-scale surveillance and the means to analyze the data in a country any kind of political opposition will be very hard.