Dylan didn't want to be just a singer he wanted to be famous singer and he was willing to go the extra mile that others around him weren't.
The other thing that sticks out is the work ethic of Dylan. A persons work ethic is more responsible for the success of a genius than the innate talent- every time.
A quick story that nailed this point home for me. In No Direction Home, they interview a hometown friend of Dylan's that says his leap in music ability from the time he left his home in Minnesota to the time he returned for a visit several months later was light years apart. It was like he sold his soul to the devil is the analogy he used. In another documentary about genius, Larry Bird- Basketball Legend, hometown friends tell the same story of Bird moving from average to great, overnight.
Of course, neither Dylan or Bird sold their soul. Dylan was just willing play and work at his skills more than most and we all know Bird shot baskets in the rain.
The people with the base talent of a Dylan or Bird are a plentiful. The people that are willing to work and improve upon their base talent and do what it takes to be known and successful are the ones that we make documentaries about.
Go down the list of great artist and athletes over the last 25 years and I guarantee you will find similar stories about each and everyone of them. Talent is needed, but ambition and work ethic are what separate the talented from the great.