Rob Gronkowski has steered into his affability and self-described “simple” nature to build one of the most in-demand personal brands of any retired athlete, putting him on a path to far surpass the almost $71 million he collected in salary and bonuses as an NFL player. Tallying up his endorsements with companies such as insurer USAA, online sportsbook FanDuel and Monster Energy along with his broadcasting gig at Fox and event appearances as a speaker or host, including the Gronk Beach festival i