I used to work for a company that sold location tracking data. It was amazing how cheap this data is and how many sources you can collect it from. We would buy

I used to work for a company that sold location tracking data. It was amazing how cheap this data is and how many sources you can collect it from. We would buy data from 3rd party sources and often have our own data sold back to us, sometimes straight up, and sometimes after randomization added to avoid exact matches. We had a whole system built to compare incoming data against our own data to make sure that we weren't having too much of our own data being sold to us.