Being a historian I tend to look at what's going on in the news from a broader perspective informed by past events. After all, the present is nothing if not the direct product of the past. I've had Donald Trump on my mind, for obvious reasons, and I think his surprising lead in the presidential primary polls is interesting from a historical point of view.
Using what we know of the past forty years of history, Trump's popularity might not actually be that surprising. Since Watergate American political culture has favored "outsiders" who are critical of a system that I think the majority of Americans has simply lost trust in (including a great many people who despise Trump.) Trump has been attacking the political process itself, and his harsh ad hominem words for John McCain and Lindsey Graham thus make him more, not less popular. By being cruel to them he is channeling the rage of the Tea Party against mainstream Republicans and Washington in general. Unlike career party politicians, Trump is free to be as nasty as he wants to be, so he can say things that would destroy the careers of others.
Furthermore, Trump is keying into the political language and style of conservative talk radio, which has been a massive force for the past thirty years. Rank and file right wingers who are used to fire-breathers like Savage and Limbaugh must be warming to Trump's crass bluntness. (Even the likes of Ted Cruz have to limit themselves in their speech.) The Right wing media has become powerful over time in framing the news and even the basic political frameworks of conservatives (I know this just from discussions with family members). While Fox and right wing talkers openly espouse racial resentment and xenophobia, politicians to be respectable have to resort to dog whistles and euphemisms. They say things like "upholding the law" and "securing the border."
Donald Trump doesn't do any of that, which is why his naked appeals to anti-immigrant hatred make him more, not less popular. This is why his Birther beliefs didn't get him discredited for life. He is just openly saying what a lot of conservatives already think. The Republican party leaders are like the sorcerer's apprentice. They have called into being a Tea Party that helps get their legions of voters to the polls, but now it has been exploited by a man who is totally outside of their control. This simply could not have happened forty years ago.
Beyond all that, I have long thought that Trump was the cultural avatar of the spirit of post-Reagan America. In the time of Andrew Carnegie wealth was accumulated in huge amounts by a small few, but Carnegie himself shamed rich men who flaunted their wealth in empty spending and failed to fund institutions for the public. The robber barons of the day stole and exploited, but they gave us parks, libraries, and universities. After the Depression and New Deal the crass wealthy were even more despised. That egalitarian spirit lasted at least forty years. As neo-liberalism began to raise its ugly head in the late 70s and its avenging angel Reagan took control of the White House, cultural values around wealth began to change. Getting rich was celebrated, more than ever, as an end in itself. The notion that wealth came with responsibility completely flew out the window. Trump went from being a real estate mogul to a celebrity in this time, flaunting both his wealth and his complete and utter selfishness. Never mind that he inherited his father's business, he became the new "self-made man."
Generally in our culture, but especially in conservative circles, it has been an article of faith that the wealthy (or "job creators") are true geniuses who know what's best for the country, and that politicians can't be trusted (not that that's not true.) Our culture has only become more celebrity and wealth obsessed as the years go on. Trump has a combination of money and celebrity that no one else can match, along with the ability to speak the political language that hardcore conservatives listen to for hours on a daily basis. Perhaps his recent political success should not surprise us.