There is already a lot of proof. Just ask for a sales pitch from companies selling these data and they will gladly explain everything to you. Go to a data conf

There is already a lot of proof. Just ask for a sales pitch from companies selling these data and they will gladly explain everything to you. Go to a data conference like Neudata and you will see. You can have scraped data from user devices, real-time locations, credit card, Google analytics, etc.