"PHILADELPHIA – Bernie Sanders said he plans to return to the Senate as an independent, despite winning 13 million votes in the Democratic Party’s presidential primary contest."
The jerk couldn't even wait to the end of the convention to sing adios to the party, after milking them for all the support and attention he could get. This is exactly why the DNC and the superdelegates were against him from the beginning- he was nothing but a parasite on the party, using it for his own purposes, and if the party does not protect itself from being used by such people, it won't have any reason to exist.
However great many of the policies Bernie supported may have been, he has revealed himself during the last six months to be a self-serving politician with little grasp of what it means to be a Democrat, and no concern for the welfare of the party. What possible reason could there ever have been for the party to allow him to be their candidate?