Much as I admire Messrs. Sowell and Cruz, I can't take that sentence seriously. Trump's ahead because (for good or ill), he draws a crowd.
There's much truth to this. Keep in mind Cruz beat Trump in Iowa, while running against the ethanol mandate.
And in more detailed and sophisticated polling, Trump's weakness is that he was almost no one's second choice. Unlike Rubio, Cruz, and even some of the dropped out candidates, who were all each other's supporters fallback positions.
Trump pulling 30% +/- is impressive when there's 6 people still running, but he is neither inevitable or a sure-thing unless he's consistently over 50% when there's only two or three of them left. (Trump, Cruz, and Rubio presumably)