The DNC and the donors and corporate backers of the Democratic AND Republican Parties would sooner see a Clinton or Trump presidency than allow Bernie Sanders anywhere near the nomination, if they can help it.
Here is the rationale, as I see it. Clinton and Trump would preserve the existing power relations in the nation. The oligarchy would not be challenged. Wall Street would retain its undue influence. Money will remain in politics and our democracy would be further eroded. Trump, despite all the talk, would do nothing to significantly disrupt the advantages of his billionaire buddies, and, of course, could not influence the DNC one way or another.
Since the parties are essentially two sides of the same coin, neither ever really loses if the flip does not go their way. It simply means that the loser's particular neo-liberal priorities are not at the top of the list this time.
Bernie Sanders and the political revolution, however, represents a real and significant challenge to the very existence of the currently constituted DNC and the oligarchic power structure. He is not one of them and could be expected to be a serious disruptive force against their power and control. He has said as much repeatedly. That group has too much to lose not to make every effort to thwart Bernie's nomination. They realize that he could handily defeat Trump, or any other pretender they can put up.
The Dem/GOP collusion to beat Bernie has long been in evidence in the behavior of all corporate media, "liberal" and conservative alike. Since the beginning, they have done everything they could to bury, discredit and marginalize his campaign. Before and during the primaries we have watched both parties engage in voter suppression efforts that have targeted likely Bernie voters. And now, in full view of everyone, we see the Clinton campaign appealing to supporters of Jeb Bush to fund Hillary!
There has long been a conversation in this country about just why low information voters tend to vote against their own interests. That conversation continues. Now, however, we need to start a new conversation, a conversation about why educated, presumably more informed voters, faced with a clear choice between a candidate firmly in the camp of the Establishment, a proponent of the status quo and, perhaps, ""incremental" change; and a candidate whose proposals closely mirror the aspirations of the majority of Americans in poll after poll, whose honesty, authenticity and integrity are beyond reproach and whose record of demonstrable commitment to social and economic justice for all Americans is fully documented; why those aforementioned people are so close to handing the first candidate the nomination. Under a Clinton Administration the nation and our working families will continue to stagnate and/or lose further ground. In whose interests are Clinton supporters voting?