Gronk's dad, while a bit of a strange bird, has built quite a little fitness-shop empire himself—before his kid became a star. He didn't use Rob's name to build it (although Rob's name doesn't hurt now). Something like 15 locations, plus a family line of weight-lifting gear. He didn't care where any of his sons went to college, so long as it had a top business school and they enrolled in it. At least two of the boys work full-time for the family business.
I don't think Rob is bright, but his dad is no dummy when it comes to money, and my guess is that Rob isn't either, at least by proxy.