there's a hardcore bass in this country who felt left behind: lost their factory jobs, not able to adapt to the information tech economy, increasingly surrounded by people from other lands who didn't look like them, speak like them, act like them, pray like them, etc. nostalgia for when things were "good". while they struggled, they felt Washington turned its back on them, bailing out banks instead of helping them. Washington establishment became the enemy, the swamp.
trump zeroed in on that sense of being aggrieved and, being the con man he is, exploited it: the ultimate outsider, the successful businessman who vowed to drain the swamp and build the wall to protect the base from those invaders from abroad. he was brash and loud, not some cultured snob who looked down on them.
to the base, trump largely does not represent the republicans, or the right, or conservative values. he represents their desire to blow up the Washington, to get back at the establishment, to stick their fingers in the eyes of the educated coastal elites.