No socialist has ever wanted to live in a socialist society run by someone who was not him.
Every socialist, in constructing his central plan, imagines that he will be the one implementing it.
The plan of every other socialist, he firmly believes, is false and counterfeit.
In the end, either Bernie will liquidate Sandy, or Sandy will liquidate Bernie. In the struggle for the rank of supreme autocrat, there can be only one man left standing.