The specific tactical modalities that took Trump from "well-known celebrity who polled well among Republicans" to "guy who beat a dozen established politicians and became the nominee" are worth recounting on their own terms. Its a story of strong, innovative behavior on Trumps part. But it's also a story of massive blundering on the part of the Republican establishment.
It's a tale in which, somewhat ironically, disciples of free market economics were brought down largely by collective action problems and an inability to coordinate.