Populism can be part of any ideology be it Trump's political base who hate intellectual ideas and call them elitist, or the Occupy movement who were the 99% against the economic inequality perpetrated by the elite, or a popular social-democracy movement which is against the elitism of state facism.

Marx thought that man's alienation was due to the separation of man from what he makes, from the products of his labor. State ideologies attempt to give reason for the labor, to force interpretation under the existing ideological frameworks, whether it's republican, democratic, socialistic, right winged or left winged, communist. However, the French Yellow Vests protests are headless, they do not have an agenda (Macron crumbled on his fuel tax) or leaders at this point...6 months of protests and counting. They appear to be the protesting of the plight of the working poor against the tax avoiding rich.

As a wall in Paris states:

"a bas le caviar vive le kebab"
"Down with caviar, long live kebab"

Population, does not bring desirable results. It is more of a Band Wagon Phenomena. Problem is sometimes the band wagon heads otu to a desolate desert, or over a cliff.

Trump is an example of populism.

Depends on what you mean by populism. If you mean politicians taking cognisance of what the majority of the population want, then that would seem to be real democracy. But if you mean the manipulation of ignorant people by billionaire-controlled media and self-serving demagogues, democracy hardly comes into it.