Mental disorder has to have both components. The Mental part is obvious here, the question for any psychologist or psychiatrist is whether or not it causes issues in the person's day to day life, outside of what a normal person experiences. There are certainly degrees of bipolar where people may die from exhaustion in a manic phase, or others who are more "get up and go" one day and don't feel like leaving the house the next.
By definition though, bipolar means you have both depressive and manic phases, and in order for it to be a depressive phase or a manic phase it is by definition a disorder. However, that doesn't mean that the person can't use it to their advantage, channel their extra energy into creativity and be successful. If you want an analogy, theres a high school/college wresther without forearms/hands or shins/feet. In his day to day life, its a "disorder", but at meets he mops the floor with normal people because he's using it to his advantage.