Back that up please.
Trump is polling at approximately 30% (depending on the poll). Trump is polling far above any of the other candidates, but collectively all of the other candidates plus undecided are polling at 70%. That means 70% do not support Trump.
As other candidates drop out, their supporters will switch to someone else. If that someone else is Trump, then Trump will win the nomination. If that someone else is not Trump, then Trump will lose.