They realize that the pendulum is shifting sides. When it has swung far, far to the Left (such as the last seven years), it must swing back at least as far to the Right, and probably farther to the Right, to maintain the equilibrium that is the United States of America.
They fear that swing back. Their problem is that it's coming.
And there is nothing they can do to stop it.
Nope, there isn't.
Trump is really problematic for them. Most of his initial support isn't from conservatives. Its from "Blue Collar' types. - Including many conservative Democrats.
They don't like Hillary.
Sanders is too far left for them.
They don't like career politicians.
So, they see the rabidly pro business, pro growth capitalist as a solution to an America in economic decline. One with a proven record of success. - Yes, a few of his ventures failed - but the 4B in his pocket suggests he has had more wins than losses.
Also, one doesn't get to be a billionaire in New York 'just because' - with all of the regulation, taxation and extra financial scrutiny as compared to nearly every other state. - Also - If Trump becomes POTUS - he will be taking a gigantic pay cut. - The only 'gains' are bragging rights, and secret service protection. (If you consider those gains.. I really don't.)
So, people are taking him at his word. Compare that to Clinton, who nobody trusts. (Sorry DUmmies, Sanders is not going to be your nominee, no matter how hard you pray to the FSM)
I don't see Trump going anywhere at this time, unless he makes a gigantic error, or decides to end his campaign.