Here is a Guardian article that gets close to explaining what is happening. The populists challenge the "rigged system" as Trump calls it, the system that the political class serve and that is run by the banks, the system that lectures the people instead of listening to them.
"Why are we surprised by every populist politician? Voting for them can be a rational choice
Commentators perplexed at the inconsistencies of Donald Trump are missing the point. Populist leaders are defined more by their style than their ideology
For at least the last 20 years, democracies around the world have been regularly subject to a mounting series of populist insurgencies. From France to Venezuela, sharp-elbowed political actors from both the left and the right have railed against elites, flouted the table manners of liberal politics, and are increasingly meeting with electoral success.
But it seems that every time this happens, it takes commentators by surprise. Witness the worldwide reaction to the rise of Donald Trump. First came denial, with even empirical journalists resisting what polling is telling them.
Now liberal journalists are in shock – for mainline conservatives it’s more like grief –as Trump continues to upend the US’s political order.
For Benjamin Moffitt, the Australian author of the new book, The Global Rise of Populism, this recurrent surprise is not only puzzling but worrying. In each country where it happens, “I think it always brings about some denial. People always see populism as just a rabble, or a problem with democracy. People want to see it as an aberration. Populism is never supposed to happen.”
He thinks it’s much more prudent to see it as a baseline feature of contemporary, mediated democracy. In the future, we should expect only more of it.
www.theguardian.com/commentisfree/2016/may/13/why-are-we-surprised-by-every-populist-politician-voting-for-them-can-be-a-rational-choice
Populists are not left or right, they combine both because their key quality is "common sense" which is why they are so successful against the elites and their political class which rely on "experts" and "spin".
Brexit was the biggest example of this populist revolution we have yet seen; Trump will be the next. The people used their "common sense" and defied the "experts", the bigwigs, the IMF, the bankers, the servants, the spin doctors, the teenage whizzkids etc etc and stunned the world.
The elites use threats, scares, Project Fear, and if they are about to lose, they sometimes turn to vote rigging partcularly with postal votes. The Austrian Freedom Party challenged the postal vote anomalies and now the elite have to run the election again.