You're right, polls showed that Sanders would do better than Clinton against Trump. The Democratic elite doesn't want Sanders because he doesn't represent their interests.
BTW, you should know that, at this point, the election is basically over and Clinton has won. This election is far too polarizing for the kind of swing Trump would need to win (people who still have hope for Trump are basically hoping for a Brexit scenario where polls significantly underestimate his support). So their strategy worked, even if it was risky.
BTW, you should know that, at this point, the election is basically over and Clinton has won. This election is far too polarizing for the kind of swing Trump would need to win (people who still have hope for Trump are basically hoping for a Brexit scenario where polls significantly underestimate his support). So their strategy worked, even if it was risky.