It seems Wild Magic is a Sorcerer class path, like how a Rogue chooses whether to be more of a poison-using assassin or a sneaky thief. Most classes have class paths, at least one of which is fairly straight-forward and similar to a standard archetype of their class (A Fighter that's better at standard combat) and alternative class paths that offer more varied options (that same fighter who instead gains access to tactical 'maneuvers' in combat).
I'd bet that there's at least one other class path for the Sorcerer that is Dragon-based. It's not even a fair bet, don't waste your money on it.