It’s not a coincidence that Trump and Sanders both promote the same economic policies.
Populism of any kind is rooted in the belief that our problems are inflicted by a secret elite, who benefit at our expense. Populists are therefore hostile towards experts and education, reject economic principles and serious policy analysis as part of the conspiracy, and promote simplistic, punitive policy ideas. Ironically, the system they’re objecting to has failed for exactly the reason their plans are always so destructive. Politicians and legislators are not policy experts. They may not reject real policy input outright, but it only tempers their intuition and prior beliefs. Even catering to special interests is generally well-intentioned, and certainly a characteristic of populists (although they don’t realize it).
It’s the failure of populism that drives these populist resurgences. If the Know-Nothings or Greenbackers had been successful, we likely would never have recovered. I don’t know if we will ever recover from the Trump/Sanders version.