PayPal is reportedly developing an advertising sales business built on its user data.The payments giant would create this ad network using data from user purchases as well as wider spending patterns from the millions of people using PayPal and Venmo, The Wall Street Journal (WSJ) reported Tuesday (May 28).According to the report, PayPal has tapped Mark Grether, one-time head of Uber’s ad business, to oversee the project as senior vice president and general manager of its newly-created PayPal Ads division.Gr ...