A College degree helps build your thinking and analytical abilities. While not exactly a requirement for becoming a sports team Coach, it would certainly help. Coaches (incl. sports coaches) win by helping their players/teams win. And that not only needs expertise and some skill in the given activity/sport - but also being able to navigate systems/leagues, analyze abilities, provide intelligent inputs, motivate, observe development and put resources in right positions. This is where having a college degree helps.